<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2020 Workiva-->
<!--r:31c88d8d-b87b-49b9-acfa-1f7fd667686d,g:a003b6f8-21a0-4e22-98ed-533019921497-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.oxy.com/role/CoverPage" xlink:type="simple" xlink:href="oxy-20200930.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CoverPage" xlink:type="extended" id="ic02a443ef60f4725ad6dad026e5a8c8e_CoverPage">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_0816ae13-0b4c-4344-9134-acf2317bdb9d" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_DocumentType_0816ae13-0b4c-4344-9134-acf2317bdb9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_89db36ef-55b0-4e85-9ca5-0692d1b78bbb" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_DocumentQuarterlyReport_89db36ef-55b0-4e85-9ca5-0692d1b78bbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_93665611-40ea-4bcf-9c55-2125c4857945" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_DocumentPeriodEndDate_93665611-40ea-4bcf-9c55-2125c4857945" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_53c6cc86-58bf-4b72-be49-a4ff6394b0c9" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_DocumentTransitionReport_53c6cc86-58bf-4b72-be49-a4ff6394b0c9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_278dd375-4375-47fb-9f89-d998e4d9887c" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityFileNumber_278dd375-4375-47fb-9f89-d998e4d9887c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_5a3c5faf-4ab4-4547-9177-a9f4decf32b3" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityRegistrantName_5a3c5faf-4ab4-4547-9177-a9f4decf32b3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_033c0fcf-0871-4739-8627-033b7ef02518" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityCentralIndexKey_033c0fcf-0871-4739-8627-033b7ef02518" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_65e01d6b-48d6-4830-be6c-0e2daa5fa8f0" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_CurrentFiscalYearEndDate_65e01d6b-48d6-4830-be6c-0e2daa5fa8f0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_a2d59838-3bf7-483b-a277-228576b16009" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_DocumentFiscalYearFocus_a2d59838-3bf7-483b-a277-228576b16009" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_fe6e195a-d8fa-423d-8af6-d21b609ca0f6" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_DocumentFiscalPeriodFocus_fe6e195a-d8fa-423d-8af6-d21b609ca0f6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_b41d2d96-4efa-4eff-bb48-31a571bf8644" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_AmendmentFlag_b41d2d96-4efa-4eff-bb48-31a571bf8644" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_ab633b29-2d35-4ac6-8daa-73857cc5eb31" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityIncorporationStateCountryCode_ab633b29-2d35-4ac6-8daa-73857cc5eb31" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_6215e29c-30b3-4a9a-b6e9-3c41cd6a0b58" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityTaxIdentificationNumber_6215e29c-30b3-4a9a-b6e9-3c41cd6a0b58" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_83ded296-3ef1-4cd8-a63e-b170cdd00071" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityAddressAddressLine1_83ded296-3ef1-4cd8-a63e-b170cdd00071" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_c95a5de1-3864-4898-a8a1-4376f9d94534" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityAddressCityOrTown_c95a5de1-3864-4898-a8a1-4376f9d94534" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_441b0361-8395-4e22-86db-854d1feb1d39" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityAddressStateOrProvince_441b0361-8395-4e22-86db-854d1feb1d39" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_1e1d2e0b-9280-443c-b26c-f72666738d8f" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityAddressPostalZipCode_1e1d2e0b-9280-443c-b26c-f72666738d8f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_b1d58469-bb1a-4239-b6f4-4d13f87c55ab" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_CityAreaCode_b1d58469-bb1a-4239-b6f4-4d13f87c55ab" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_a25d3b7b-b2cc-48f1-a40c-be068a1c461c" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_LocalPhoneNumber_a25d3b7b-b2cc-48f1-a40c-be068a1c461c" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_76084a60-5138-4aa4-8917-5aa01e2ddfa8" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_Security12bTitle_76084a60-5138-4aa4-8917-5aa01e2ddfa8" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_e48f3fe4-8764-4940-862a-7377a7748520" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_TradingSymbol_e48f3fe4-8764-4940-862a-7377a7748520" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_efa7a028-ab16-4ed5-8a44-0522fc370989" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_SecurityExchangeName_efa7a028-ab16-4ed5-8a44-0522fc370989" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_b2b661ee-cecf-4617-99b7-dbb90b3e8c39" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityCurrentReportingStatus_b2b661ee-cecf-4617-99b7-dbb90b3e8c39" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_e7bc7d48-e161-42b6-b752-3701900236e2" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityInteractiveDataCurrent_e7bc7d48-e161-42b6-b752-3701900236e2" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_502f35c4-497f-47b1-a7ef-35d97bd4e6ba" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityFilerCategory_502f35c4-497f-47b1-a7ef-35d97bd4e6ba" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_f6bf9f19-318d-4dba-8b9c-a9658ec3e28f" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntitySmallBusiness_f6bf9f19-318d-4dba-8b9c-a9658ec3e28f" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_0a953e8b-adca-4b02-a99d-bf8dc2bfae9a" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityEmergingGrowthCompany_0a953e8b-adca-4b02-a99d-bf8dc2bfae9a" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_f6c0a4d7-5a6a-402b-ba61-e9bff49c4e00" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityShellCompany_f6c0a4d7-5a6a-402b-ba61-e9bff49c4e00" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_a626e646-f809-4982-a6d0-6384a7ee5679" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_a626e646-f809-4982-a6d0-6384a7ee5679" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_1f4d314d-95f2-4a5e-803b-45208aa698e8" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_aec3eff0-4791-49ec-bd31-332bef378c84" xlink:to="loc_dei_EntitiesTable_1f4d314d-95f2-4a5e-803b-45208aa698e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_54edd0fa-4dcd-4470-84b1-7e1ff71387b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_1f4d314d-95f2-4a5e-803b-45208aa698e8" xlink:to="loc_us-gaap_StatementClassOfStockAxis_54edd0fa-4dcd-4470-84b1-7e1ff71387b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_54edd0fa-4dcd-4470-84b1-7e1ff71387b7_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_54edd0fa-4dcd-4470-84b1-7e1ff71387b7" xlink:to="loc_us-gaap_ClassOfStockDomain_54edd0fa-4dcd-4470-84b1-7e1ff71387b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e5a2c0e3-7bcd-4196-bae9-68dfa6a29b29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_54edd0fa-4dcd-4470-84b1-7e1ff71387b7" xlink:to="loc_us-gaap_ClassOfStockDomain_e5a2c0e3-7bcd-4196-bae9-68dfa6a29b29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_6cded201-bbf6-4db0-8ad9-0d9db29ad211" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e5a2c0e3-7bcd-4196-bae9-68dfa6a29b29" xlink:to="loc_us-gaap_CommonStockMember_6cded201-bbf6-4db0-8ad9-0d9db29ad211" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_WarrantsToPurchaseCommonStockMember_8b317160-d224-47ec-9688-47d609795423" xlink:href="oxy-20200930.xsd#oxy_WarrantsToPurchaseCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e5a2c0e3-7bcd-4196-bae9-68dfa6a29b29" xlink:to="loc_oxy_WarrantsToPurchaseCommonStockMember_8b317160-d224-47ec-9688-47d609795423" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDBALANCESHEETS" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDBALANCESHEETS" xlink:type="extended" id="i1029564cd94d41afa48128a50c40a784_CONSOLIDATEDCONDENSEDBALANCESHEETS">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_10e84225-71f4-4a62-b05f-5791a5bb206d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_10e84225-71f4-4a62-b05f-5791a5bb206d" xlink:to="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_f0ea36f3-b398-40a0-80f1-1549ff756712" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_f0ea36f3-b398-40a0-80f1-1549ff756712" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_82d59557-2c33-429f-884d-dc356cfd3a0b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_82d59557-2c33-429f-884d-dc356cfd3a0b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_cf07d5f6-94a5-4cf9-9992-7e6d7c84d955" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_cf07d5f6-94a5-4cf9-9992-7e6d7c84d955" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_f7aac3e3-0cb4-4e4a-ab58-8c50f17cb013" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_InventoryNet_f7aac3e3-0cb4-4e4a-ab58-8c50f17cb013" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsCurrent_bc920706-664c-4137-80b7-032eeb8688b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_OtherAssetsCurrent_bc920706-664c-4137-80b7-032eeb8688b0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrent_3c15e769-9970-4b39-9853-ee6c2d904019" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_AssetsHeldForSaleNotPartOfDisposalGroupCurrent_3c15e769-9970-4b39-9853-ee6c2d904019" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_df47f8ae-29c4-4cac-a321-6a8fee4c8785" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_067035ec-2698-43f0-aef9-3aab51b35b5e" xlink:to="loc_us-gaap_AssetsCurrent_df47f8ae-29c4-4cac-a321-6a8fee4c8785" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_88099f09-b587-4d01-90c9-2aec65736a92" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_EquityMethodInvestments_88099f09-b587-4d01-90c9-2aec65736a92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_d397651e-cedd-42c6-b45c-03898a7c6fef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_d397651e-cedd-42c6-b45c-03898a7c6fef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_d9afa74e-41f3-49fd-a726-6d90084ac2c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_d9afa74e-41f3-49fd-a726-6d90084ac2c0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_ce7fa7a4-02f9-4120-bf4f-f324389d0c05" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_ce7fa7a4-02f9-4120-bf4f-f324389d0c05" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_37f4add1-2231-44ad-b2cf-28b18eac0518" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_37f4add1-2231-44ad-b2cf-28b18eac0518" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LongTermReceivablesAndOtherNoncurrentAssetsNet_820d5920-819b-4d9b-867a-4d51da655e7b" xlink:href="oxy-20200930.xsd#oxy_LongTermReceivablesAndOtherNoncurrentAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_oxy_LongTermReceivablesAndOtherNoncurrentAssetsNet_820d5920-819b-4d9b-867a-4d51da655e7b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_113c0819-edc4-4f7f-995b-6dfb40ea2828" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_9014c092-5099-43af-b5e7-910435f53626" xlink:to="loc_us-gaap_Assets_113c0819-edc4-4f7f-995b-6dfb40ea2828" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_10e84225-71f4-4a62-b05f-5791a5bb206d" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_760e8842-a237-423c-a7b2-b7aa1e60e38a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:to="loc_us-gaap_LongTermDebtCurrent_760e8842-a237-423c-a7b2-b7aa1e60e38a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_fdb8266e-5e46-4f8c-b458-7e0fa9ccfddb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_fdb8266e-5e46-4f8c-b458-7e0fa9ccfddb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_8a51f06c-e3c0-4796-ba78-4705b8448133" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:to="loc_us-gaap_AccountsPayableCurrent_8a51f06c-e3c0-4796-ba78-4705b8448133" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_cb9f89fb-2002-4fab-8099-4b1775b0d909" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_cb9f89fb-2002-4fab-8099-4b1775b0d909" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_CurrentLiabilitiesAssociatedWithAssetsHeldforSale_d7740bc0-c47c-4e5c-8df5-61e0041866d1" xlink:href="oxy-20200930.xsd#oxy_CurrentLiabilitiesAssociatedWithAssetsHeldforSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:to="loc_oxy_CurrentLiabilitiesAssociatedWithAssetsHeldforSale_d7740bc0-c47c-4e5c-8df5-61e0041866d1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_8a551fc0-d0b2-4027-a096-aa162d5c733d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_47115965-e3a8-4f37-9daa-e5522f031dec" xlink:to="loc_us-gaap_LiabilitiesCurrent_8a551fc0-d0b2-4027-a096-aa162d5c733d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrentAbstract_b9d0ed17-760a-4785-b3fe-d0f93b1806b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:to="loc_us-gaap_LongTermDebtNoncurrentAbstract_b9d0ed17-760a-4785-b3fe-d0f93b1806b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_137aec1a-2967-4ca4-9d96-4af2085a1f3c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtNoncurrentAbstract_b9d0ed17-760a-4785-b3fe-d0f93b1806b7" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_137aec1a-2967-4ca4-9d96-4af2085a1f3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:to="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_7cf69b68-9b74-4942-8086-24f95795ddc9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_7cf69b68-9b74-4942-8086-24f95795ddc9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationsNoncurrent_f608ab11-526e-42f3-a975-e745dfec34e7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetRetirementObligationsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_AssetRetirementObligationsNoncurrent_f608ab11-526e-42f3-a975-e745dfec34e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_5c0be0a3-971b-46d5-b779-899e5f229494" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_5c0be0a3-971b-46d5-b779-899e5f229494" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_43134c1d-0ed9-415c-bc18-7db1b94a4957" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_43134c1d-0ed9-415c-bc18-7db1b94a4957" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_96f77ad0-7574-443d-9666-1d9c1d5b4d9b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_96f77ad0-7574-443d-9666-1d9c1d5b4d9b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_85e0992b-3d9b-4a67-9ab8-f3566cf428d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_85e0992b-3d9b-4a67-9ab8-f3566cf428d9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesNoncurrent_473671d4-a146-4482-8cbb-571108752d91" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCreditsAndOtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesAbstract_ba472cd9-cafd-4f7b-ba50-49490cbc1687" xlink:to="loc_us-gaap_DeferredCreditsAndOtherLiabilitiesNoncurrent_473671d4-a146-4482-8cbb-571108752d91" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:to="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_17d9b24d-5510-48e2-8fa1-bbb7c7b71726" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_PreferredStockValue_17d9b24d-5510-48e2-8fa1-bbb7c7b71726" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_c0537a66-b158-4589-885c-228ae3a31edc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_CommonStockValue_c0537a66-b158-4589-885c-228ae3a31edc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValue_7ea91ac7-0ad9-4f9f-87e0-383c8636a385" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_TreasuryStockValue_7ea91ac7-0ad9-4f9f-87e0-383c8636a385" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_14c146f6-c151-4c96-b85f-533f87635648" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_AdditionalPaidInCapital_14c146f6-c151-4c96-b85f-533f87635648" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_3bd3bf73-2119-4b8e-89ff-bf9041b5fc18" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_3bd3bf73-2119-4b8e-89ff-bf9041b5fc18" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_f951aabe-1f69-43fb-b5c4-5b56147c43f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_f951aabe-1f69-43fb-b5c4-5b56147c43f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_0c282fab-2ebb-43e0-9d4a-9e570489793c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_a089301d-0548-4873-97ea-91dbb8b3f85f" xlink:to="loc_us-gaap_StockholdersEquity_0c282fab-2ebb-43e0-9d4a-9e570489793c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_9746d939-7ca8-482a-8b98-09429cc893d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_e3f96c9c-a83e-48be-b7bc-6791a818e3f4" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_9746d939-7ca8-482a-8b98-09429cc893d4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_62b1eeda-c6f2-4416-8826-ec0c80aa6c79" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_10e84225-71f4-4a62-b05f-5791a5bb206d" xlink:to="loc_us-gaap_StatementTable_62b1eeda-c6f2-4416-8826-ec0c80aa6c79" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_48b04531-c094-49a9-a932-6ba1fe5b051e" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_62b1eeda-c6f2-4416-8826-ec0c80aa6c79" xlink:to="loc_srt_ConsolidationItemsAxis_48b04531-c094-49a9-a932-6ba1fe5b051e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_48b04531-c094-49a9-a932-6ba1fe5b051e_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_48b04531-c094-49a9-a932-6ba1fe5b051e" xlink:to="loc_srt_ConsolidationItemsDomain_48b04531-c094-49a9-a932-6ba1fe5b051e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ddafeff4-4b0a-42bc-8457-22fff7654192" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_48b04531-c094-49a9-a932-6ba1fe5b051e" xlink:to="loc_srt_ConsolidationItemsDomain_ddafeff4-4b0a-42bc-8457-22fff7654192" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_171cd7db-8c47-4c47-b57d-7d0ccddb5bec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ddafeff4-4b0a-42bc-8457-22fff7654192" xlink:to="loc_us-gaap_CorporateNonSegmentMember_171cd7db-8c47-4c47-b57d-7d0ccddb5bec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1d14d995-d6bb-4172-807f-6583a922bf24" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_62b1eeda-c6f2-4416-8826-ec0c80aa6c79" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1d14d995-d6bb-4172-807f-6583a922bf24" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1d14d995-d6bb-4172-807f-6583a922bf24_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1d14d995-d6bb-4172-807f-6583a922bf24" xlink:to="loc_us-gaap_SegmentDomain_1d14d995-d6bb-4172-807f-6583a922bf24_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0fa9abaf-6151-44e3-bb3b-32745fe5eb95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1d14d995-d6bb-4172-807f-6583a922bf24" xlink:to="loc_us-gaap_SegmentDomain_0fa9abaf-6151-44e3-bb3b-32745fe5eb95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasSegmentMember_db2e392b-b272-4642-9f0a-ee7889ff3ef8" xlink:href="oxy-20200930.xsd#oxy_OilAndGasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0fa9abaf-6151-44e3-bb3b-32745fe5eb95" xlink:to="loc_oxy_OilAndGasSegmentMember_db2e392b-b272-4642-9f0a-ee7889ff3ef8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ChemicalSegmentMember_186367e7-f7d2-42df-9ade-2ffc6eb2cd2b" xlink:href="oxy-20200930.xsd#oxy_ChemicalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0fa9abaf-6151-44e3-bb3b-32745fe5eb95" xlink:to="loc_oxy_ChemicalSegmentMember_186367e7-f7d2-42df-9ade-2ffc6eb2cd2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MidstreamSegmentMember_87006833-5d31-4fab-ad9f-f1cceee216e6" xlink:href="oxy-20200930.xsd#oxy_MidstreamSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0fa9abaf-6151-44e3-bb3b-32745fe5eb95" xlink:to="loc_oxy_MidstreamSegmentMember_87006833-5d31-4fab-ad9f-f1cceee216e6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDBALANCESHEETSParenthetical"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDBALANCESHEETSParenthetical" xlink:type="extended" id="i9deeb4cf5e894c708082a29f9f4c3717_CONSOLIDATEDCONDENSEDBALANCESHEETSParenthetical"/>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFOPERATIONS" xlink:type="extended" id="ifafb5bce626b412b915476cc1c4ff660_CONSOLIDATEDCONDENSEDSTATEMENTSOFOPERATIONS"/>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS" xlink:type="extended" id="ied68bdd9e73d4c679b828f79c091dff4_CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS"/>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSSParenthetical" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSSParenthetical"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSSParenthetical" xlink:type="extended" id="ide1ca045e9b5462faa7d76bab83defd0_CONSOLIDATEDCONDENSEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSSParenthetical"/>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFCASHFLOWS" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDSTATEMENTSOFCASHFLOWS"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFCASHFLOWS" xlink:type="extended" id="ib548e1db24cf42fe87bf61f3f336c8f2_CONSOLIDATEDCONDENSEDSTATEMENTSOFCASHFLOWS"/>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITY" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITY"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITY" xlink:type="extended" id="i45e23eec3b5643d6849a499173e365d1_CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITY">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_d31b0d43-d2b0-409e-b027-1d01d390392b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d31b0d43-d2b0-409e-b027-1d01d390392b" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_d85b776f-3ba7-40d6-8e3d-3187567867c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_d85b776f-3ba7-40d6-8e3d-3187567867c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_97abf01a-63c1-4ac2-a1b5-f92878159945" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_ProfitLoss_97abf01a-63c1-4ac2-a1b5-f92878159945" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_23b70422-8379-4887-8f9d-cb45efb2f43b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_23b70422-8379-4887-8f9d-cb45efb2f43b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_21627cc1-d2df-4b03-9f21-22698f2e2940" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_DividendsCommonStockCash_21627cc1-d2df-4b03-9f21-22698f2e2940" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_eb3cb6ff-e592-4927-aaad-6692b1686cc8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_DividendsPreferredStockCash_eb3cb6ff-e592-4927-aaad-6692b1686cc8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_IssuanceOfCommonStockAndOtherNet_561c9444-e00f-40b8-985f-4c7753ef1cd6" xlink:href="oxy-20200930.xsd#oxy_IssuanceOfCommonStockAndOtherNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_oxy_IssuanceOfCommonStockAndOtherNet_561c9444-e00f-40b8-985f-4c7753ef1cd6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants_b8dae487-6454-4bb3-ad46-3c9ec3df14fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants_b8dae487-6454-4bb3-ad46-3c9ec3df14fe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_68f9ccd9-b9d1-421c-a9d1-14d71f126778" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued_68f9ccd9-b9d1-421c-a9d1-14d71f126778" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClassOfWarrantOrRightValueIssued_26d93950-5428-422a-b196-47cd374338c9" xlink:href="oxy-20200930.xsd#oxy_ClassOfWarrantOrRightValueIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_oxy_ClassOfWarrantOrRightValueIssued_26d93950-5428-422a-b196-47cd374338c9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_5f8cabca-1fbe-47fd-9eb0-2eabd1a4b2b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_5f8cabca-1fbe-47fd-9eb0-2eabd1a4b2b8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_587d426d-70d8-4836-80e2-a229c8349b31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_587d426d-70d8-4836-80e2-a229c8349b31" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_2f7b7916-ce53-4041-9751-67d0c49a9f3e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_be9bdf09-219c-4881-aab3-ea7fb3ea022c" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_2f7b7916-ce53-4041-9751-67d0c49a9f3e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_4d57e1d8-02df-46ce-8c5d-880fda22c2d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_bac18ca6-d202-45c9-92c3-3f32e923258e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_d31b0d43-d2b0-409e-b027-1d01d390392b" xlink:to="loc_us-gaap_StatementTable_bac18ca6-d202-45c9-92c3-3f32e923258e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_c537a1ca-b56b-4328-87da-29b4df1f21a1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_bac18ca6-d202-45c9-92c3-3f32e923258e" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_c537a1ca-b56b-4328-87da-29b4df1f21a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_c537a1ca-b56b-4328-87da-29b4df1f21a1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_c537a1ca-b56b-4328-87da-29b4df1f21a1" xlink:to="loc_us-gaap_EquityComponentDomain_c537a1ca-b56b-4328-87da-29b4df1f21a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_c537a1ca-b56b-4328-87da-29b4df1f21a1" xlink:to="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_b4aa9fe7-a3ec-4938-88cb-8001cb2dec13" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_PreferredStockMember_b4aa9fe7-a3ec-4938-88cb-8001cb2dec13" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_152cf6c6-be26-4bc2-86c9-fac0b908c120" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_CommonStockMember_152cf6c6-be26-4bc2-86c9-fac0b908c120" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_5887fc28-3665-405d-b65a-8c40e949b75e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_TreasuryStockMember_5887fc28-3665-405d-b65a-8c40e949b75e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_02244395-a7e8-45b1-a3bd-c63c050aafcb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_02244395-a7e8-45b1-a3bd-c63c050aafcb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_201acc7e-238c-4005-91d5-49124bc67e05" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_RetainedEarningsMember_201acc7e-238c-4005-91d5-49124bc67e05" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_938dc795-e6b8-4546-98e7-cc677f82d246" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_938dc795-e6b8-4546-98e7-cc677f82d246" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_a074be41-2d67-4c9a-9031-0788015e09fb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4c2db10-954e-4ce7-be4d-717e2a3dce45" xlink:to="loc_us-gaap_NoncontrollingInterestMember_a074be41-2d67-4c9a-9031-0788015e09fb" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITYParenthetical" xlink:type="simple" xlink:href="oxy-20200930.xsd#CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITYParenthetical"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITYParenthetical" xlink:type="extended" id="i73d5dcd7bd2b4d328efa37b4ef3f33d0_CONSOLIDATEDCONDENSEDSTATEMENTSOFEQUITYParenthetical"/>
  <link:roleRef roleURI="http://www.oxy.com/role/General" xlink:type="simple" xlink:href="oxy-20200930.xsd#General"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/General" xlink:type="extended" id="ie7ff554a285f4b77a6988c43806ab0fa_General"/>
  <link:roleRef roleURI="http://www.oxy.com/role/GeneralPolicies" xlink:type="simple" xlink:href="oxy-20200930.xsd#GeneralPolicies"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/GeneralPolicies" xlink:type="extended" id="ie1fde0a7b624428fb5113f85b93abd90_GeneralPolicies"/>
  <link:roleRef roleURI="http://www.oxy.com/role/GeneralTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#GeneralTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/GeneralTables" xlink:type="extended" id="ia460dd61aef141239466569bde94255d_GeneralTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/GeneralDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#GeneralDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/GeneralDetails" xlink:type="extended" id="ia487229da8c343f38c458d8522034d58_GeneralDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_cc879636-2b2f-4767-bdeb-3f9fffba5607" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_cc879636-2b2f-4767-bdeb-3f9fffba5607" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_86536fc6-2388-4170-a8fd-4435612a4ec0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_AssetImpairmentCharges_86536fc6-2388-4170-a8fd-4435612a4ec0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaid_a71c639e-c29a-4047-8d50-5b286272b85d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxesPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_IncomeTaxesPaid_a71c639e-c29a-4047-8d50-5b286272b85d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIncomeTaxRefunds_81bb18d2-9b8a-4ca1-a1e7-fccf40a9cc2e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIncomeTaxRefunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_ProceedsFromIncomeTaxRefunds_81bb18d2-9b8a-4ca1-a1e7-fccf40a9cc2e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_deb32667-d1fd-4488-83b6-b29c0498c623" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_InterestPaidNet_deb32667-d1fd-4488-83b6-b29c0498c623" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_0c5adcd4-faee-4d45-83b6-b824e949c5f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_0c5adcd4-faee-4d45-83b6-b824e949c5f8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_2f40b351-1abc-4e17-bb37-e03e238e98a3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue_2f40b351-1abc-4e17-bb37-e03e238e98a3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCashAndRestrictedCash_f98da94e-be15-4a05-bdea-c1949a72bb4d" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationCashAndRestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCashAndRestrictedCash_f98da94e-be15-4a05-bdea-c1949a72bb4d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashEquivalentsNoncurrent_20766f86-d3a1-4403-b7fe-0d177f17e522" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedCashEquivalentsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_RestrictedCashEquivalentsNoncurrent_20766f86-d3a1-4403-b7fe-0d177f17e522" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_06580120-814c-4e68-9bd1-633e880bfa65" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_06580120-814c-4e68-9bd1-633e880bfa65" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_3be70867-cc06-47fe-a5cd-72fd5e761793" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_EquityMethodInvestments_3be70867-cc06-47fe-a5cd-72fd5e761793" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest_f5ff2be0-e512-49c5-a8ab-22bce9f3c12c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest_f5ff2be0-e512-49c5-a8ab-22bce9f3c12c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_487b1fda-bca1-4a3f-aee8-7f60d36fdec9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_487b1fda-bca1-4a3f-aee8-7f60d36fdec9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_68e63b6b-343c-4e6c-bd31-ad5ba8b53c74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_68e63b6b-343c-4e6c-bd31-ad5ba8b53c74" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_RelatedPartyTransactionLossInNonCashTransaction_03352f6f-a492-4e99-b92b-1ee7e1705e17" xlink:href="oxy-20200930.xsd#oxy_RelatedPartyTransactionLossInNonCashTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_RelatedPartyTransactionLossInNonCashTransaction_03352f6f-a492-4e99-b92b-1ee7e1705e17" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_RelatedPartiesCommonUnitsIssuedInNotesPayableRetirement_d77aa6a6-6f25-4f54-a3a9-b66baef76ad7" xlink:href="oxy-20200930.xsd#oxy_RelatedPartiesCommonUnitsIssuedInNotesPayableRetirement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_RelatedPartiesCommonUnitsIssuedInNotesPayableRetirement_d77aa6a6-6f25-4f54-a3a9-b66baef76ad7" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_NotesPayableRelatedPartiesAmountRetired_fa11fe1b-bdd8-4f2b-8826-2567b0cad0f8" xlink:href="oxy-20200930.xsd#oxy_NotesPayableRelatedPartiesAmountRetired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_NotesPayableRelatedPartiesAmountRetired_fa11fe1b-bdd8-4f2b-8826-2567b0cad0f8" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPNonVotingGeneralPartnerUnitInterestPercentage_41aa4f11-217d-4893-8960-b95ad45f9e36" xlink:href="oxy-20200930.xsd#oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPNonVotingGeneralPartnerUnitInterestPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPNonVotingGeneralPartnerUnitInterestPercentage_41aa4f11-217d-4893-8960-b95ad45f9e36" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPLimitedPartnerUnitOwnershipInterest_028c2ded-c552-4373-9406-771329448305" xlink:href="oxy-20200930.xsd#oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPLimitedPartnerUnitOwnershipInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPLimitedPartnerUnitOwnershipInterest_028c2ded-c552-4373-9406-771329448305" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPEffectiveEconomicInterestPercentage_fd7baa6e-18eb-440e-92a9-9ca5e9e142fd" xlink:href="oxy-20200930.xsd#oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPEffectiveEconomicInterestPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPEffectiveEconomicInterestPercentage_fd7baa6e-18eb-440e-92a9-9ca5e9e142fd" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPOwnershipReductionPercentage_55c814e0-e974-4211-a36d-75858bf11269" xlink:href="oxy-20200930.xsd#oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPOwnershipReductionPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPOwnershipReductionPercentage_55c814e0-e974-4211-a36d-75858bf11269" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPProRataOfNetAssets_0664ecf8-19e3-4081-b2fa-59c34b3dd563" xlink:href="oxy-20200930.xsd#oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPProRataOfNetAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_oxy_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPProRataOfNetAssets_0664ecf8-19e3-4081-b2fa-59c34b3dd563" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromRelatedParties_c3aabab8-436b-40c4-a008-ea4e4e3cf40f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_RevenueFromRelatedParties_c3aabab8-436b-40c4-a008-ea4e4e3cf40f" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_a213e4d5-8acb-4563-b5e4-2113cc43837e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty_a213e4d5-8acb-4563-b5e4-2113cc43837e" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MinorityInterestLineItems_a25df6fd-9a6a-4670-bf16-eb6c59a207c3" xlink:to="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_50048a6c-9239-4e8c-95eb-fa661f29ba45" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_50048a6c-9239-4e8c-95eb-fa661f29ba45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_50048a6c-9239-4e8c-95eb-fa661f29ba45_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_50048a6c-9239-4e8c-95eb-fa661f29ba45" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_50048a6c-9239-4e8c-95eb-fa661f29ba45_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_221dbf47-9dd7-4dfd-9f3d-46444f4d2bc4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_50048a6c-9239-4e8c-95eb-fa661f29ba45" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_221dbf47-9dd7-4dfd-9f3d-46444f4d2bc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_66a71ea9-f13b-400b-b857-459915f18b00" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_221dbf47-9dd7-4dfd-9f3d-46444f4d2bc4" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_66a71ea9-f13b-400b-b857-459915f18b00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ef587c4b-6731-45d8-bd02-d5f5026ac9b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ef587c4b-6731-45d8-bd02-d5f5026ac9b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_ef587c4b-6731-45d8-bd02-d5f5026ac9b7_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ef587c4b-6731-45d8-bd02-d5f5026ac9b7" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_ef587c4b-6731-45d8-bd02-d5f5026ac9b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_da3c56b4-18db-48a4-8af0-198a7b840874" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_ef587c4b-6731-45d8-bd02-d5f5026ac9b7" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_da3c56b4-18db-48a4-8af0-198a7b840874" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AlgeriaAfricaAssetsMember_29338254-bccd-431b-b313-f2b809213a09" xlink:href="oxy-20200930.xsd#oxy_AlgeriaAfricaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_da3c56b4-18db-48a4-8af0-198a7b840874" xlink:to="loc_oxy_AlgeriaAfricaAssetsMember_29338254-bccd-431b-b313-f2b809213a09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GhanaAssetsMember_de647bff-1389-4dc2-848b-b60310c1f1d3" xlink:href="oxy-20200930.xsd#oxy_GhanaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_da3c56b4-18db-48a4-8af0-198a7b840874" xlink:to="loc_oxy_GhanaAssetsMember_de647bff-1389-4dc2-848b-b60310c1f1d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_f85d7483-4bcd-4437-9cb8-6810c5264c85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_f85d7483-4bcd-4437-9cb8-6810c5264c85" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_f85d7483-4bcd-4437-9cb8-6810c5264c85_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_f85d7483-4bcd-4437-9cb8-6810c5264c85" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_f85d7483-4bcd-4437-9cb8-6810c5264c85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_4ed41008-c3a3-4d41-9f25-f77511e83177" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_f85d7483-4bcd-4437-9cb8-6810c5264c85" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_4ed41008-c3a3-4d41-9f25-f77511e83177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_a6dc9048-e379-4395-b54e-7fce2f96e1f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_4ed41008-c3a3-4d41-9f25-f77511e83177" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_a6dc9048-e379-4395-b54e-7fce2f96e1f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_086263f4-2b79-4314-aae7-07a2dbf2eeee" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_srt_CounterpartyNameAxis_086263f4-2b79-4314-aae7-07a2dbf2eeee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_086263f4-2b79-4314-aae7-07a2dbf2eeee_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_086263f4-2b79-4314-aae7-07a2dbf2eeee" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_086263f4-2b79-4314-aae7-07a2dbf2eeee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_623083f9-84cb-42a1-8de7-ad3231e54279" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_086263f4-2b79-4314-aae7-07a2dbf2eeee" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_623083f9-84cb-42a1-8de7-ad3231e54279" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_93b30b7d-6773-46f0-84d3-0fd38df31c6a" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_623083f9-84cb-42a1-8de7-ad3231e54279" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_93b30b7d-6773-46f0-84d3-0fd38df31c6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a04c290-e2f9-46db-bf9a-1ce090f30e95" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a04c290-e2f9-46db-bf9a-1ce090f30e95" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_8a04c290-e2f9-46db-bf9a-1ce090f30e95_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a04c290-e2f9-46db-bf9a-1ce090f30e95" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_8a04c290-e2f9-46db-bf9a-1ce090f30e95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_b378116a-a1a8-4cea-aff1-d6ee95e386af" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_8a04c290-e2f9-46db-bf9a-1ce090f30e95" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_b378116a-a1a8-4cea-aff1-d6ee95e386af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_WesternMidstreamPartnersLPMember_987dd238-6c39-4ebe-accc-ba9ed974ecdd" xlink:href="oxy-20200930.xsd#oxy_WesternMidstreamPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_b378116a-a1a8-4cea-aff1-d6ee95e386af" xlink:to="loc_oxy_WesternMidstreamPartnersLPMember_987dd238-6c39-4ebe-accc-ba9ed974ecdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_0be1f4ff-57c8-456c-9d1e-d8d7ee975781" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_dei_LegalEntityAxis_0be1f4ff-57c8-456c-9d1e-d8d7ee975781" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_0be1f4ff-57c8-456c-9d1e-d8d7ee975781_default" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_0be1f4ff-57c8-456c-9d1e-d8d7ee975781" xlink:to="loc_dei_EntityDomain_0be1f4ff-57c8-456c-9d1e-d8d7ee975781_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_3981e2d1-f146-4006-ab32-3b05818eb406" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_0be1f4ff-57c8-456c-9d1e-d8d7ee975781" xlink:to="loc_dei_EntityDomain_3981e2d1-f146-4006-ab32-3b05818eb406" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PublicOwnershipMember_f8e6b88d-a4b6-4784-af9d-88d24ca61d98" xlink:href="oxy-20200930.xsd#oxy_PublicOwnershipMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_3981e2d1-f146-4006-ab32-3b05818eb406" xlink:to="loc_oxy_PublicOwnershipMember_f8e6b88d-a4b6-4784-af9d-88d24ca61d98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_6d3b7b19-495d-436f-9bf7-e80357fe0fd2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_srt_OwnershipAxis_6d3b7b19-495d-436f-9bf7-e80357fe0fd2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_6d3b7b19-495d-436f-9bf7-e80357fe0fd2_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_6d3b7b19-495d-436f-9bf7-e80357fe0fd2" xlink:to="loc_srt_OwnershipDomain_6d3b7b19-495d-436f-9bf7-e80357fe0fd2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_d71db78f-9853-4035-9ffa-d3ab2416efa4" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_6d3b7b19-495d-436f-9bf7-e80357fe0fd2" xlink:to="loc_srt_OwnershipDomain_d71db78f-9853-4035-9ffa-d3ab2416efa4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_WesternMidstreamPartnersLPMember_3f715d9a-d23a-4be4-945a-f893338097a5" xlink:href="oxy-20200930.xsd#oxy_WesternMidstreamPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_d71db78f-9853-4035-9ffa-d3ab2416efa4" xlink:to="loc_oxy_WesternMidstreamPartnersLPMember_3f715d9a-d23a-4be4-945a-f893338097a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_39422308-0c7c-431d-8c64-3671a6c93e78" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_39422308-0c7c-431d-8c64-3671a6c93e78" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_39422308-0c7c-431d-8c64-3671a6c93e78_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_39422308-0c7c-431d-8c64-3671a6c93e78" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_39422308-0c7c-431d-8c64-3671a6c93e78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_851ac3a5-564f-479e-9e8a-3912315b0d8b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesAxis_39422308-0c7c-431d-8c64-3671a6c93e78" xlink:to="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_851ac3a5-564f-479e-9e8a-3912315b0d8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_4f598ad8-0db6-417a-b4d4-89511a8ba1f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentsByConsolidatedAndNonconsolidatedEntitiesDomain_851ac3a5-564f-479e-9e8a-3912315b0d8b" xlink:to="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_4f598ad8-0db6-417a-b4d4-89511a8ba1f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a929ab-7045-4ccd-8228-7fa127740c6b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a929ab-7045-4ccd-8228-7fa127740c6b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a929ab-7045-4ccd-8228-7fa127740c6b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a929ab-7045-4ccd-8228-7fa127740c6b" xlink:to="loc_us-gaap_RelatedPartyDomain_01a929ab-7045-4ccd-8228-7fa127740c6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_3aaa2fab-2e18-488b-a404-3febff21f483" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a929ab-7045-4ccd-8228-7fa127740c6b" xlink:to="loc_us-gaap_RelatedPartyDomain_3aaa2fab-2e18-488b-a404-3febff21f483" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_f9e1b917-e7b0-4004-98e9-945d7329252a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_3aaa2fab-2e18-488b-a404-3febff21f483" xlink:to="loc_srt_AffiliatedEntityMember_f9e1b917-e7b0-4004-98e9-945d7329252a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_aeb4d73d-429d-48bc-9a3f-635c7d4096f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_b675d51a-179c-4db2-8c3b-f199a2f2520b" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_aeb4d73d-429d-48bc-9a3f-635c7d4096f1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_aeb4d73d-429d-48bc-9a3f-635c7d4096f1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_aeb4d73d-429d-48bc-9a3f-635c7d4096f1" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_aeb4d73d-429d-48bc-9a3f-635c7d4096f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_9cb4b004-92e5-4a96-8beb-141bf16fe95c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_aeb4d73d-429d-48bc-9a3f-635c7d4096f1" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_9cb4b004-92e5-4a96-8beb-141bf16fe95c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GeneralPurchasesMember_9b2445ec-99b8-4b72-85dc-c80dc3471dad" xlink:href="oxy-20200930.xsd#oxy_GeneralPurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_9cb4b004-92e5-4a96-8beb-141bf16fe95c" xlink:to="loc_oxy_GeneralPurchasesMember_9b2445ec-99b8-4b72-85dc-c80dc3471dad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_TransportationGatheringAndOtherFeesPaidMember_ae63b03b-9f6c-411e-acb7-d305142ee399" xlink:href="oxy-20200930.xsd#oxy_TransportationGatheringAndOtherFeesPaidMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_9cb4b004-92e5-4a96-8beb-141bf16fe95c" xlink:to="loc_oxy_TransportationGatheringAndOtherFeesPaidMember_ae63b03b-9f6c-411e-acb7-d305142ee399" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/AccountingandDisclosureChanges" xlink:type="simple" xlink:href="oxy-20200930.xsd#AccountingandDisclosureChanges"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/AccountingandDisclosureChanges" xlink:type="extended" id="i4c31f8f8622747998b94ebf409336e49_AccountingandDisclosureChanges"/>
  <link:roleRef roleURI="http://www.oxy.com/role/DivestituresandOtherTransactions" xlink:type="simple" xlink:href="oxy-20200930.xsd#DivestituresandOtherTransactions"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DivestituresandOtherTransactions" xlink:type="extended" id="id2adaca3948647bd87202ac9dff7253f_DivestituresandOtherTransactions"/>
  <link:roleRef roleURI="http://www.oxy.com/role/DivestituresandOtherTransactionsTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#DivestituresandOtherTransactionsTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DivestituresandOtherTransactionsTables" xlink:type="extended" id="i854761f49c95480f92b4b1eee0f1cde2_DivestituresandOtherTransactionsTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/DivestituresandOtherTransactionsNarrativeDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DivestituresandOtherTransactionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DivestituresandOtherTransactionsNarrativeDetails" xlink:type="extended" id="i843cff8e40fb4e028ec3929c8fad856a_DivestituresandOtherTransactionsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationAreaOfLandSold_ddc1d989-ad6e-49c2-9198-9ee164a4ddfa" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationAreaOfLandSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationAreaOfLandSold_ddc1d989-ad6e-49c2-9198-9ee164a4ddfa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationFeeSurfaceAreaSold_d25ba8d3-3b9b-4555-9b4c-a54ffb59febb" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationFeeSurfaceAreaSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationFeeSurfaceAreaSold_d25ba8d3-3b9b-4555-9b4c-a54ffb59febb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_32ce8b7f-a8c1-4c94-b630-ffc26276f355" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_32ce8b7f-a8c1-4c94-b630-ffc26276f355" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_ebd97e7b-e5c8-405e-9127-ac64dc136c4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_ebd97e7b-e5c8-405e-9127-ac64dc136c4e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationLiabilitiesSettledRelatedToFutureRoyalties_7071d231-5d58-4abd-85bc-bcdc6373c8f9" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationLiabilitiesSettledRelatedToFutureRoyalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationLiabilitiesSettledRelatedToFutureRoyalties_7071d231-5d58-4abd-85bc-bcdc6373c8f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_23a75ac4-e201-4e69-bb95-fe8509e868da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_23a75ac4-e201-4e69-bb95-fe8509e868da" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_2a3e2585-e2cd-4eaf-afad-36915714c7bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_2a3e2585-e2cd-4eaf-afad-36915714c7bc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_e71706b4-0610-4fcc-b7b0-7101b960a7bc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_e71706b4-0610-4fcc-b7b0-7101b960a7bc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_3179a82e-02c3-495c-95a4-ec5f198ede29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_DebtInstrumentTerm_3179a82e-02c3-495c-95a4-ec5f198ede29" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown_2cb3705c-06f6-4c6a-99c9-8b33ad18a609" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown_2cb3705c-06f6-4c6a-99c9-8b33ad18a609" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_ae000973-aa34-4c8c-810a-13f4c77f9b59" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_ae000973-aa34-4c8c-810a-13f4c77f9b59" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_da7d9ce2-c364-48df-a9bc-87bb9f4fd8e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_AssetImpairmentCharges_da7d9ce2-c364-48df-a9bc-87bb9f4fd8e9" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7e206696-6a91-43fd-b1e2-6c1db1d15a8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_adbd852f-9aa8-4a0c-a69a-5d003f3eca2f" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7e206696-6a91-43fd-b1e2-6c1db1d15a8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_749074a1-59ab-4d35-8864-e32376e93a46" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7e206696-6a91-43fd-b1e2-6c1db1d15a8a" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_749074a1-59ab-4d35-8864-e32376e93a46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_749074a1-59ab-4d35-8864-e32376e93a46_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_749074a1-59ab-4d35-8864-e32376e93a46" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_749074a1-59ab-4d35-8864-e32376e93a46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_b398b6ca-2597-46fa-9949-41b1fd38c654" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_749074a1-59ab-4d35-8864-e32376e93a46" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_b398b6ca-2597-46fa-9949-41b1fd38c654" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_f0d66847-8907-4ad0-a89f-2500b1c82dd3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_b398b6ca-2597-46fa-9949-41b1fd38c654" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_f0d66847-8907-4ad0-a89f-2500b1c82dd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_42e1565c-5194-4dad-9ed3-cc0106e40fb0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_b398b6ca-2597-46fa-9949-41b1fd38c654" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_42e1565c-5194-4dad-9ed3-cc0106e40fb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d1709733-8d36-45e8-ad70-5a2fabe99bd6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7e206696-6a91-43fd-b1e2-6c1db1d15a8a" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d1709733-8d36-45e8-ad70-5a2fabe99bd6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d1709733-8d36-45e8-ad70-5a2fabe99bd6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d1709733-8d36-45e8-ad70-5a2fabe99bd6" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d1709733-8d36-45e8-ad70-5a2fabe99bd6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e9370dc1-68c3-4a87-808b-5159ecd42e87" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d1709733-8d36-45e8-ad70-5a2fabe99bd6" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e9370dc1-68c3-4a87-808b-5159ecd42e87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_WyomingColoradoAndUtahAssetsMember_4db12531-172b-44af-991e-f0e7af26e4f9" xlink:href="oxy-20200930.xsd#oxy_WyomingColoradoAndUtahAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e9370dc1-68c3-4a87-808b-5159ecd42e87" xlink:to="loc_oxy_WyomingColoradoAndUtahAssetsMember_4db12531-172b-44af-991e-f0e7af26e4f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ColumbiaAssetsMember_104fe075-fca7-4979-9b18-b3acbbaa8536" xlink:href="oxy-20200930.xsd#oxy_ColumbiaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e9370dc1-68c3-4a87-808b-5159ecd42e87" xlink:to="loc_oxy_ColumbiaAssetsMember_104fe075-fca7-4979-9b18-b3acbbaa8536" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GhanaAssetsMember_ff671202-70f3-4212-9691-f9d0326f23a2" xlink:href="oxy-20200930.xsd#oxy_GhanaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e9370dc1-68c3-4a87-808b-5159ecd42e87" xlink:to="loc_oxy_GhanaAssetsMember_ff671202-70f3-4212-9691-f9d0326f23a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_4ab4417d-4680-4ac8-bd43-a4f451a936e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7e206696-6a91-43fd-b1e2-6c1db1d15a8a" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_4ab4417d-4680-4ac8-bd43-a4f451a936e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_4ab4417d-4680-4ac8-bd43-a4f451a936e1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_4ab4417d-4680-4ac8-bd43-a4f451a936e1" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_4ab4417d-4680-4ac8-bd43-a4f451a936e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_74cab7d9-fe89-46e1-8889-b8e9b81f6fe4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_4ab4417d-4680-4ac8-bd43-a4f451a936e1" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_74cab7d9-fe89-46e1-8889-b8e9b81f6fe4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_08aa5cc9-2b67-4f1a-9a46-076cef608be1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_74cab7d9-fe89-46e1-8889-b8e9b81f6fe4" xlink:to="loc_us-gaap_SubsequentEventMember_08aa5cc9-2b67-4f1a-9a46-076cef608be1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_89ca7437-9d88-4ee7-90dd-5686420e28b2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_7e206696-6a91-43fd-b1e2-6c1db1d15a8a" xlink:to="loc_us-gaap_DebtInstrumentAxis_89ca7437-9d88-4ee7-90dd-5686420e28b2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_89ca7437-9d88-4ee7-90dd-5686420e28b2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_89ca7437-9d88-4ee7-90dd-5686420e28b2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_89ca7437-9d88-4ee7-90dd-5686420e28b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_6db7b1b1-31cc-4f65-a148-56213cf012d1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_89ca7437-9d88-4ee7-90dd-5686420e28b2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_6db7b1b1-31cc-4f65-a148-56213cf012d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_VariableRateBondsDue2021Member_fff8c993-431a-422b-aebf-771c70fdc7a6" xlink:href="oxy-20200930.xsd#oxy_VariableRateBondsDue2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6db7b1b1-31cc-4f65-a148-56213cf012d1" xlink:to="loc_oxy_VariableRateBondsDue2021Member_fff8c993-431a-422b-aebf-771c70fdc7a6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DivestituresandOtherTransactionsSummaryofRevenuesandCostsfromDiscontinuedOperationsDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DivestituresandOtherTransactionsSummaryofRevenuesandCostsfromDiscontinuedOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DivestituresandOtherTransactionsSummaryofRevenuesandCostsfromDiscontinuedOperationsDetails" xlink:type="extended" id="ia7b278e615df425291334c4d91950f9e_DivestituresandOtherTransactionsSummaryofRevenuesandCostsfromDiscontinuedOperationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationRevenueAndOtherIncomeAbstract_1337feeb-6fc5-4b2f-b619-eeb673831c89" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationRevenueAndOtherIncomeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationRevenueAndOtherIncomeAbstract_1337feeb-6fc5-4b2f-b619-eeb673831c89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_820c2e18-683c-4be6-90af-e8f4a17930c7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationRevenueAndOtherIncomeAbstract_1337feeb-6fc5-4b2f-b619-eeb673831c89" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_820c2e18-683c-4be6-90af-e8f4a17930c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_3df98ce6-c56a-4e57-900c-df4aa279736a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_3df98ce6-c56a-4e57-900c-df4aa279736a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationTransportationAndMarketingExpense_0c4f2b0e-be91-42fa-a245-c38993081a97" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationTransportationAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationTransportationAndMarketingExpense_0c4f2b0e-be91-42fa-a245-c38993081a97" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationTaxesOtherThanOnIncome_91232b30-2a93-4038-8d4b-5312ebaee7cf" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationTaxesOtherThanOnIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationTaxesOtherThanOnIncome_91232b30-2a93-4038-8d4b-5312ebaee7cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization_7ef2c8ff-a941-4bd9-ab4d-1eda2d9550ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDepreciationAndAmortization_7ef2c8ff-a941-4bd9-ab4d-1eda2d9550ba" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationImpairmentUponReclassificationToHeldForUse_766c40a4-c91a-4edb-aebd-bbcf718277b1" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationImpairmentUponReclassificationToHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationImpairmentUponReclassificationToHeldForUse_766c40a4-c91a-4edb-aebd-bbcf718277b1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense_c7250922-9da5-4334-ac2f-9934f8b0823e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherExpense_c7250922-9da5-4334-ac2f-9934f8b0823e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsNet_3a1b80f0-a687-4491-afe0-2f27a45622f1" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsAbstract_d8b545b2-934e-4116-b81f-fc9e7d23ad98" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationCostsAndOtherDeductionsNet_3a1b80f0-a687-4491-afe0-2f27a45622f1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_adbdb75d-d622-433d-a338-d6384b146de1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_adbdb75d-d622-433d-a338-d6384b146de1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_750366ba-666b-4890-9eb2-311079f3ca19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_750366ba-666b-4890-9eb2-311079f3ca19" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_bb251eb4-e021-4a68-8a06-a93854955392" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_bb251eb4-e021-4a68-8a06-a93854955392" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_e2d7527e-a899-4216-8fc8-0e0fd5d89af7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_975a52e3-2cae-4921-bd1d-f8b411648335" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_e2d7527e-a899-4216-8fc8-0e0fd5d89af7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96800898-9587-4a57-bb3b-be3b979ba129" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_e2d7527e-a899-4216-8fc8-0e0fd5d89af7" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96800898-9587-4a57-bb3b-be3b979ba129" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_96800898-9587-4a57-bb3b-be3b979ba129_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96800898-9587-4a57-bb3b-be3b979ba129" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_96800898-9587-4a57-bb3b-be3b979ba129_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_49d620be-ea51-42a3-b861-080ea688690a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96800898-9587-4a57-bb3b-be3b979ba129" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_49d620be-ea51-42a3-b861-080ea688690a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AlgeriaAfricaAssetsMember_93d0b09c-c6a2-42fd-a3e1-20ba7e1a842d" xlink:href="oxy-20200930.xsd#oxy_AlgeriaAfricaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_49d620be-ea51-42a3-b861-080ea688690a" xlink:to="loc_oxy_AlgeriaAfricaAssetsMember_93d0b09c-c6a2-42fd-a3e1-20ba7e1a842d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_18665a74-67de-4e7b-b232-9a8fa1dcb50a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_e2d7527e-a899-4216-8fc8-0e0fd5d89af7" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_18665a74-67de-4e7b-b232-9a8fa1dcb50a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_18665a74-67de-4e7b-b232-9a8fa1dcb50a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_18665a74-67de-4e7b-b232-9a8fa1dcb50a" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_18665a74-67de-4e7b-b232-9a8fa1dcb50a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_8026721f-aa2a-49f0-8ad9-f91e1082e2b4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_18665a74-67de-4e7b-b232-9a8fa1dcb50a" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_8026721f-aa2a-49f0-8ad9-f91e1082e2b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_135ac1f7-62b9-4106-a5f8-5c3a0cf0c496" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_8026721f-aa2a-49f0-8ad9-f91e1082e2b4" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_135ac1f7-62b9-4106-a5f8-5c3a0cf0c496" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DivestituresandOtherTransactionsSummaryofAssetsHeldforSaleDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DivestituresandOtherTransactionsSummaryofAssetsHeldforSaleDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DivestituresandOtherTransactionsSummaryofAssetsHeldforSaleDetails" xlink:type="extended" id="i49b9cb1f7fd84a1b93e3f60aafb89b92_DivestituresandOtherTransactionsSummaryofAssetsHeldforSaleDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_bde9197f-ebf7-45ec-8e96-beaae2e68e6a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_bde9197f-ebf7-45ec-8e96-beaae2e68e6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_3bcf185b-88f0-4447-98d0-477cbcf8479b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_3bcf185b-88f0-4447-98d0-477cbcf8479b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DisposalGroupIncludingDiscontinuedOperationNoncurrentReceivablesandOtherAssetsNet_6a419bfc-dbfc-4f67-8e6b-f84fa16eb8e9" xlink:href="oxy-20200930.xsd#oxy_DisposalGroupIncludingDiscontinuedOperationNoncurrentReceivablesandOtherAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_oxy_DisposalGroupIncludingDiscontinuedOperationNoncurrentReceivablesandOtherAssetsNet_6a419bfc-dbfc-4f67-8e6b-f84fa16eb8e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_b7a04932-2c51-4430-86ee-9685c5292061" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_b7a04932-2c51-4430-86ee-9685c5292061" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_35b1083b-eeae-4d37-b860-79f27c3b3aed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_35b1083b-eeae-4d37-b860-79f27c3b3aed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities_7c8138ed-7fc6-4aef-8d5a-e8477609329d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities_7c8138ed-7fc6-4aef-8d5a-e8477609329d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_6b814114-66f1-478a-8114-d8407c6a242f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_6b814114-66f1-478a-8114-d8407c6a242f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_3f1999b0-09a5-47bb-b686-0e2b8cf13366" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_5652d5a6-6901-4b2d-bb5e-9c8eb5b80218" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_3f1999b0-09a5-47bb-b686-0e2b8cf13366" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_07e21e30-980e-4f7b-b78f-55f8f6c05c75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_3f1999b0-09a5-47bb-b686-0e2b8cf13366" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_07e21e30-980e-4f7b-b78f-55f8f6c05c75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_07e21e30-980e-4f7b-b78f-55f8f6c05c75_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_07e21e30-980e-4f7b-b78f-55f8f6c05c75" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_07e21e30-980e-4f7b-b78f-55f8f6c05c75_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_15d7af85-d935-4116-9672-62765ea09eff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_07e21e30-980e-4f7b-b78f-55f8f6c05c75" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_15d7af85-d935-4116-9672-62765ea09eff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AlgeriaAfricaAssetsMember_7d1cc86a-05ce-4de3-a6b5-3f5ab110e7bd" xlink:href="oxy-20200930.xsd#oxy_AlgeriaAfricaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_15d7af85-d935-4116-9672-62765ea09eff" xlink:to="loc_oxy_AlgeriaAfricaAssetsMember_7d1cc86a-05ce-4de3-a6b5-3f5ab110e7bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_f49ea693-3f3c-495e-98e9-77f1f8a37e72" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_3f1999b0-09a5-47bb-b686-0e2b8cf13366" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_f49ea693-3f3c-495e-98e9-77f1f8a37e72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_f49ea693-3f3c-495e-98e9-77f1f8a37e72_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_f49ea693-3f3c-495e-98e9-77f1f8a37e72" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_f49ea693-3f3c-495e-98e9-77f1f8a37e72_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_7886eb46-49c9-469b-846a-763137d7c102" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_f49ea693-3f3c-495e-98e9-77f1f8a37e72" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_7886eb46-49c9-469b-846a-763137d7c102" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_a1c6bc42-f9d5-4e85-b376-f234b69721a1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_7886eb46-49c9-469b-846a-763137d7c102" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_a1c6bc42-f9d5-4e85-b376-f234b69721a1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/Revenue" xlink:type="simple" xlink:href="oxy-20200930.xsd#Revenue"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/Revenue" xlink:type="extended" id="i558341de3dd540aab66fc8fbcc1c1f00_Revenue"/>
  <link:roleRef roleURI="http://www.oxy.com/role/RevenueTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#RevenueTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RevenueTables" xlink:type="extended" id="i5f0ed1042de24f4eabe6e7071389581a_RevenueTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/RevenueImpactofAdoptionDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#RevenueImpactofAdoptionDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RevenueImpactofAdoptionDetails" xlink:type="extended" id="i4f233f1bc5f44d679c20758e70ce9da2_RevenueImpactofAdoptionDetails"/>
  <link:roleRef roleURI="http://www.oxy.com/role/RevenueReconciliationDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#RevenueReconciliationDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RevenueReconciliationDetails" xlink:type="extended" id="i6b3fc5383090476c9a91866474069ee5_RevenueReconciliationDetails"/>
  <link:roleRef roleURI="http://www.oxy.com/role/RevenueDisaggregationofrevenueDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#RevenueDisaggregationofrevenueDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RevenueDisaggregationofrevenueDetails" xlink:type="extended" id="i80aa3d1327f24ff1b240b7960fc5aa96_RevenueDisaggregationofrevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_8dc89650-eae9-4c51-9fcd-b560b666f13b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_16fcbabe-08df-47ff-9dad-2df4578deaee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_8dc89650-eae9-4c51-9fcd-b560b666f13b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_16fcbabe-08df-47ff-9dad-2df4578deaee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_b80b4ef4-ba34-4ed3-8d88-c98a6c665955" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_8dc89650-eae9-4c51-9fcd-b560b666f13b" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_b80b4ef4-ba34-4ed3-8d88-c98a6c665955" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_c34cd360-46f2-49bb-a833-4fce2c181cfb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_b80b4ef4-ba34-4ed3-8d88-c98a6c665955" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_c34cd360-46f2-49bb-a833-4fce2c181cfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_c34cd360-46f2-49bb-a833-4fce2c181cfb_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_c34cd360-46f2-49bb-a833-4fce2c181cfb" xlink:to="loc_us-gaap_SegmentDomain_c34cd360-46f2-49bb-a833-4fce2c181cfb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9d8b91f5-86b5-47ef-ab2f-b56828f54460" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_c34cd360-46f2-49bb-a833-4fce2c181cfb" xlink:to="loc_us-gaap_SegmentDomain_9d8b91f5-86b5-47ef-ab2f-b56828f54460" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasSegmentMember_28c5d3bf-7d75-4f5e-b583-fbceba3f0289" xlink:href="oxy-20200930.xsd#oxy_OilAndGasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9d8b91f5-86b5-47ef-ab2f-b56828f54460" xlink:to="loc_oxy_OilAndGasSegmentMember_28c5d3bf-7d75-4f5e-b583-fbceba3f0289" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ChemicalSegmentMember_beda6a19-06b4-4150-805f-021bf956c6f7" xlink:href="oxy-20200930.xsd#oxy_ChemicalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9d8b91f5-86b5-47ef-ab2f-b56828f54460" xlink:to="loc_oxy_ChemicalSegmentMember_beda6a19-06b4-4150-805f-021bf956c6f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MidstreamSegmentMember_6957d2cc-d2f5-40e4-91d6-e805721b4f35" xlink:href="oxy-20200930.xsd#oxy_MidstreamSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9d8b91f5-86b5-47ef-ab2f-b56828f54460" xlink:to="loc_oxy_MidstreamSegmentMember_6957d2cc-d2f5-40e4-91d6-e805721b4f35" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_WesternMidstreamPartnersLPMember_3823dec4-6123-48b1-8708-ae54bc63bf80" xlink:href="oxy-20200930.xsd#oxy_WesternMidstreamPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9d8b91f5-86b5-47ef-ab2f-b56828f54460" xlink:to="loc_oxy_WesternMidstreamPartnersLPMember_3823dec4-6123-48b1-8708-ae54bc63bf80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_beca8a8c-ef9c-4b5e-bd7c-ec860c54af13" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_b80b4ef4-ba34-4ed3-8d88-c98a6c665955" xlink:to="loc_srt_ConsolidationItemsAxis_beca8a8c-ef9c-4b5e-bd7c-ec860c54af13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_beca8a8c-ef9c-4b5e-bd7c-ec860c54af13_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_beca8a8c-ef9c-4b5e-bd7c-ec860c54af13" xlink:to="loc_srt_ConsolidationItemsDomain_beca8a8c-ef9c-4b5e-bd7c-ec860c54af13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_bbbee25c-ef1f-41a9-90ac-e78699790b57" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_beca8a8c-ef9c-4b5e-bd7c-ec860c54af13" xlink:to="loc_srt_ConsolidationItemsDomain_bbbee25c-ef1f-41a9-90ac-e78699790b57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_9b2a0981-2c3b-4fa0-8c69-a5202af07c2b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_bbbee25c-ef1f-41a9-90ac-e78699790b57" xlink:to="loc_us-gaap_IntersegmentEliminationMember_9b2a0981-2c3b-4fa0-8c69-a5202af07c2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_4ab4ff06-8363-417c-9a37-d88ea76a4b33" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_b80b4ef4-ba34-4ed3-8d88-c98a6c665955" xlink:to="loc_srt_StatementGeographicalAxis_4ab4ff06-8363-417c-9a37-d88ea76a4b33" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_4ab4ff06-8363-417c-9a37-d88ea76a4b33_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_4ab4ff06-8363-417c-9a37-d88ea76a4b33" xlink:to="loc_srt_SegmentGeographicalDomain_4ab4ff06-8363-417c-9a37-d88ea76a4b33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_89f06acd-b507-4b25-9205-8a9f8cdeeb40" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_4ab4ff06-8363-417c-9a37-d88ea76a4b33" xlink:to="loc_srt_SegmentGeographicalDomain_89f06acd-b507-4b25-9205-8a9f8cdeeb40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_d4c37323-cc5a-4dc7-b911-fcad9ea02a68" xlink:href="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_89f06acd-b507-4b25-9205-8a9f8cdeeb40" xlink:to="loc_country_US_d4c37323-cc5a-4dc7-b911-fcad9ea02a68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MiddleEastMember_febaf5c8-fe04-4864-b71e-340c3019e92c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MiddleEastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_89f06acd-b507-4b25-9205-8a9f8cdeeb40" xlink:to="loc_us-gaap_MiddleEastMember_febaf5c8-fe04-4864-b71e-340c3019e92c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LatinAmericaMember_e39954ef-6ef6-42fe-bdd2-c0a33350e883" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_LatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_89f06acd-b507-4b25-9205-8a9f8cdeeb40" xlink:to="loc_srt_LatinAmericaMember_e39954ef-6ef6-42fe-bdd2-c0a33350e883" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OtherCountriesExcludingUsMiddleEastLatinAmericaMember_bfc7ba72-aeec-4d13-a447-3c41ecb29b6b" xlink:href="oxy-20200930.xsd#oxy_OtherCountriesExcludingUsMiddleEastLatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_89f06acd-b507-4b25-9205-8a9f8cdeeb40" xlink:to="loc_oxy_OtherCountriesExcludingUsMiddleEastLatinAmericaMember_bfc7ba72-aeec-4d13-a447-3c41ecb29b6b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_cbf1c1d3-df1b-4b41-9b9e-e7ca53fdd9c5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_b80b4ef4-ba34-4ed3-8d88-c98a6c665955" xlink:to="loc_srt_ProductOrServiceAxis_cbf1c1d3-df1b-4b41-9b9e-e7ca53fdd9c5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_cbf1c1d3-df1b-4b41-9b9e-e7ca53fdd9c5_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_cbf1c1d3-df1b-4b41-9b9e-e7ca53fdd9c5" xlink:to="loc_srt_ProductsAndServicesDomain_cbf1c1d3-df1b-4b41-9b9e-e7ca53fdd9c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_cbf1c1d3-df1b-4b41-9b9e-e7ca53fdd9c5" xlink:to="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OilReservesMember_9c22834a-bc41-4148-ae0d-2943b0bb6e3b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OilReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_srt_OilReservesMember_9c22834a-bc41-4148-ae0d-2943b0bb6e3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasLiquidsReservesMember_2ebb5748-c93d-4078-932b-5bf2352b6997" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NaturalGasLiquidsReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_srt_NaturalGasLiquidsReservesMember_2ebb5748-c93d-4078-932b-5bf2352b6997" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasReservesMember_76e1c9fd-56cd-4a26-8164-f96e4d94b947" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NaturalGasReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_srt_NaturalGasReservesMember_76e1c9fd-56cd-4a26-8164-f96e4d94b947" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductAndServiceOtherMember_e65c47ac-dab2-41dc-82d7-d4becccdea24" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProductAndServiceOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_us-gaap_ProductAndServiceOtherMember_e65c47ac-dab2-41dc-82d7-d4becccdea24" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GasProcessingMember_c03bbcab-a205-48aa-acb1-b24e38ecd6db" xlink:href="oxy-20200930.xsd#oxy_GasProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_oxy_GasProcessingMember_c03bbcab-a205-48aa-acb1-b24e38ecd6db" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MarketingMember_b164b10f-2aca-4054-97ee-3f84786e1ff1" xlink:href="oxy-20200930.xsd#oxy_MarketingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_oxy_MarketingMember_b164b10f-2aca-4054-97ee-3f84786e1ff1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PowerAndOtherMember_ea14eec6-0b20-41a7-bea3-8716bb9dbd44" xlink:href="oxy-20200930.xsd#oxy_PowerAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_f2189c8f-d09b-468b-a7c9-562deaedd32d" xlink:to="loc_oxy_PowerAndOtherMember_ea14eec6-0b20-41a7-bea3-8716bb9dbd44" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/RevenueScheduleofExpectedFutureRevenueDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#RevenueScheduleofExpectedFutureRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RevenueScheduleofExpectedFutureRevenueDetails" xlink:type="extended" id="i12ca311df4814b538fcceb912e16811c_RevenueScheduleofExpectedFutureRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_5d8966c5-28ff-4f92-bb42-42f200bb47dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_5d8966c5-28ff-4f92-bb42-42f200bb47dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_eaad5e4a-78a9-4e47-ab04-99aaf91d7854" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_eaad5e4a-78a9-4e47-ab04-99aaf91d7854" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_42185dd1-a65d-49fe-bd13-d82c6a87d651" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_42185dd1-a65d-49fe-bd13-d82c6a87d651" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_f00a516a-4cc3-45b9-a140-e1485a518b9c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_42185dd1-a65d-49fe-bd13-d82c6a87d651" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_f00a516a-4cc3-45b9-a140-e1485a518b9c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/RevenueScheduleofExpectedFutureRevenueDetails_1" xlink:type="simple" xlink:href="oxy-20200930.xsd#RevenueScheduleofExpectedFutureRevenueDetails_1"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RevenueScheduleofExpectedFutureRevenueDetails_1" xlink:type="extended" id="i0af6264a42f14f63994c27e55e9fde2a_RevenueScheduleofExpectedFutureRevenueDetails_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_5d8966c5-28ff-4f92-bb42-42f200bb47dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_5d8966c5-28ff-4f92-bb42-42f200bb47dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_eaad5e4a-78a9-4e47-ab04-99aaf91d7854" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_eaad5e4a-78a9-4e47-ab04-99aaf91d7854" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_42185dd1-a65d-49fe-bd13-d82c6a87d651" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f9e98722-5729-43d9-b52d-9f12a240ffad" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_42185dd1-a65d-49fe-bd13-d82c6a87d651" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/Inventory" xlink:type="simple" xlink:href="oxy-20200930.xsd#Inventory"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/Inventory" xlink:type="extended" id="ied4a370f2df848d78fb1ba11fd2f630f_Inventory"/>
  <link:roleRef roleURI="http://www.oxy.com/role/InventoryTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#InventoryTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/InventoryTables" xlink:type="extended" id="i641ecb43e122468384e5c4d9eb95b24d_InventoryTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/InventoryDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#InventoryDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/InventoryDetails" xlink:type="extended" id="ic28510d12cdb4c3d9afb8b84d605b862_InventoryDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryLineItems_4b011a29-2447-42f3-8ce4-12787ce0c8cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown_b3ddd113-d708-4c8b-b947-211903f50634" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_4b011a29-2447-42f3-8ce4-12787ce0c8cf" xlink:to="loc_us-gaap_InventoryWriteDown_b3ddd113-d708-4c8b-b947-211903f50634" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryCurrentTable_7172b7ef-1561-44d8-a50a-dff91328cb83" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryCurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_InventoryLineItems_4b011a29-2447-42f3-8ce4-12787ce0c8cf" xlink:to="loc_us-gaap_InventoryCurrentTable_7172b7ef-1561-44d8-a50a-dff91328cb83" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_1ac75c8e-68d0-4f2c-96f1-89af2899d441" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PublicUtilitiesInventoryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_7172b7ef-1561-44d8-a50a-dff91328cb83" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_1ac75c8e-68d0-4f2c-96f1-89af2899d441" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_1ac75c8e-68d0-4f2c-96f1-89af2899d441_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_1ac75c8e-68d0-4f2c-96f1-89af2899d441" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_1ac75c8e-68d0-4f2c-96f1-89af2899d441_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_00e33e6b-486e-47df-8fda-e153a92b218a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_1ac75c8e-68d0-4f2c-96f1-89af2899d441" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_00e33e6b-486e-47df-8fda-e153a92b218a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_CommodityInventoriesMember_9322af77-fa2f-42bd-a715-a0c83d59086c" xlink:href="oxy-20200930.xsd#oxy_CommodityInventoriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_00e33e6b-486e-47df-8fda-e153a92b218a" xlink:to="loc_oxy_CommodityInventoriesMember_9322af77-fa2f-42bd-a715-a0c83d59086c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/Derivatives" xlink:type="simple" xlink:href="oxy-20200930.xsd#Derivatives"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/Derivatives" xlink:type="extended" id="i262cba9bfa304e50b87ab3d173a69ca0_Derivatives"/>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesTables" xlink:type="extended" id="ic4010172fc93493195bbc537c881333c_DerivativesTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesDerivativeInstrumentsDetails" xlink:type="extended" id="i48398ff60ca3485baf27f12dc4668fc6_DerivativesDerivativeInstrumentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_a7bea163-7ba9-41cf-8231-c4cf98fbb001" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities_372cbf90-1cd5-4471-ab98-9fc0a301e317" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a7bea163-7ba9-41cf-8231-c4cf98fbb001" xlink:to="loc_us-gaap_ProceedsFromDerivativeInstrumentInvestingActivities_372cbf90-1cd5-4471-ab98-9fc0a301e317" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DerivativeContractualCommodityPrice_1dda141a-a1ee-43c9-ae7b-d4b3e6ddc13f" xlink:href="oxy-20200930.xsd#oxy_DerivativeContractualCommodityPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a7bea163-7ba9-41cf-8231-c4cf98fbb001" xlink:to="loc_oxy_DerivativeContractualCommodityPrice_1dda141a-a1ee-43c9-ae7b-d4b3e6ddc13f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageCapPrice_ae581d90-5767-4e91-983f-44b85e5eea2f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeAverageCapPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a7bea163-7ba9-41cf-8231-c4cf98fbb001" xlink:to="loc_us-gaap_DerivativeAverageCapPrice_ae581d90-5767-4e91-983f-44b85e5eea2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageFloorPrice_fb2dee5a-dfab-4a48-9d5e-8f91f566a41d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeAverageFloorPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_a7bea163-7ba9-41cf-8231-c4cf98fbb001" xlink:to="loc_us-gaap_DerivativeAverageFloorPrice_fb2dee5a-dfab-4a48-9d5e-8f91f566a41d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_a7bea163-7ba9-41cf-8231-c4cf98fbb001" xlink:to="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_a145bff1-d0c7-4f8f-8d97-072717fa7982" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:to="loc_us-gaap_HedgingDesignationAxis_a145bff1-d0c7-4f8f-8d97-072717fa7982" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_a145bff1-d0c7-4f8f-8d97-072717fa7982_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_a145bff1-d0c7-4f8f-8d97-072717fa7982" xlink:to="loc_us-gaap_HedgingDesignationDomain_a145bff1-d0c7-4f8f-8d97-072717fa7982_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_a9bc8b3b-25f5-4574-9dde-865faff51a30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_a145bff1-d0c7-4f8f-8d97-072717fa7982" xlink:to="loc_us-gaap_HedgingDesignationDomain_a9bc8b3b-25f5-4574-9dde-865faff51a30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_de6a27a0-ee21-4a90-b4ea-ffab388466de" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_a9bc8b3b-25f5-4574-9dde-865faff51a30" xlink:to="loc_us-gaap_NondesignatedMember_de6a27a0-ee21-4a90-b4ea-ffab388466de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_ad0eaded-9ce7-426b-994c-f461289d4079" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_ad0eaded-9ce7-426b-994c-f461289d4079" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ad0eaded-9ce7-426b-994c-f461289d4079_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ad0eaded-9ce7-426b-994c-f461289d4079" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ad0eaded-9ce7-426b-994c-f461289d4079_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_9ae41cf5-f4eb-4925-95de-921847cdd1c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_ad0eaded-9ce7-426b-994c-f461289d4079" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_9ae41cf5-f4eb-4925-95de-921847cdd1c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_87cbcb26-2796-46cf-900a-a936d181adb1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_9ae41cf5-f4eb-4925-95de-921847cdd1c5" xlink:to="loc_us-gaap_SubsequentEventMember_87cbcb26-2796-46cf-900a-a936d181adb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_033d1623-8515-4881-aceb-561ef1aa8f97" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_033d1623-8515-4881-aceb-561ef1aa8f97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_033d1623-8515-4881-aceb-561ef1aa8f97_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_033d1623-8515-4881-aceb-561ef1aa8f97" xlink:to="loc_us-gaap_EquityComponentDomain_033d1623-8515-4881-aceb-561ef1aa8f97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_c0f0c0e4-4861-4966-b08a-9268b25802d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_033d1623-8515-4881-aceb-561ef1aa8f97" xlink:to="loc_us-gaap_EquityComponentDomain_c0f0c0e4-4861-4966-b08a-9268b25802d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_fb06f8a3-46e8-4e8e-a83a-cc455cbd988c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c0f0c0e4-4861-4966-b08a-9268b25802d4" xlink:to="loc_us-gaap_CommonStockMember_fb06f8a3-46e8-4e8e-a83a-cc455cbd988c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_4acc3dfe-cdff-4e6a-a227-ff9f2fbc8742" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:to="loc_srt_EnergyAxis_4acc3dfe-cdff-4e6a-a227-ff9f2fbc8742" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_4acc3dfe-cdff-4e6a-a227-ff9f2fbc8742_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_4acc3dfe-cdff-4e6a-a227-ff9f2fbc8742" xlink:to="loc_srt_EnergyDomain_4acc3dfe-cdff-4e6a-a227-ff9f2fbc8742_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_957cc169-78f0-42f0-8112-8bf88b1daf8c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_4acc3dfe-cdff-4e6a-a227-ff9f2fbc8742" xlink:to="loc_srt_EnergyDomain_957cc169-78f0-42f0-8112-8bf88b1daf8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CrudeOilMember_1053f936-5feb-4300-a4e8-fffedb6c4656" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CrudeOilMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_957cc169-78f0-42f0-8112-8bf88b1daf8c" xlink:to="loc_srt_CrudeOilMember_1053f936-5feb-4300-a4e8-fffedb6c4656" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasReservesMember_7dfd8b57-122e-47b3-ba7e-bf08547e08d9" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NaturalGasReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_957cc169-78f0-42f0-8112-8bf88b1daf8c" xlink:to="loc_srt_NaturalGasReservesMember_7dfd8b57-122e-47b3-ba7e-bf08547e08d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_76060090-53c2-46c6-9f30-677dd69eefe1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_76060090-53c2-46c6-9f30-677dd69eefe1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_76060090-53c2-46c6-9f30-677dd69eefe1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_76060090-53c2-46c6-9f30-677dd69eefe1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_76060090-53c2-46c6-9f30-677dd69eefe1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f14208f2-1db8-4ba7-9154-e38aed2027c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_76060090-53c2-46c6-9f30-677dd69eefe1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f14208f2-1db8-4ba7-9154-e38aed2027c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_bc41894a-87a0-4e7a-a4ce-3663eb7e8d3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f14208f2-1db8-4ba7-9154-e38aed2027c2" xlink:to="loc_us-gaap_WarrantMember_bc41894a-87a0-4e7a-a4ce-3663eb7e8d3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_Settlement2020Member_7e714d72-664a-4ef3-a679-d678377f3145" xlink:href="oxy-20200930.xsd#oxy_Settlement2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f14208f2-1db8-4ba7-9154-e38aed2027c2" xlink:to="loc_oxy_Settlement2020Member_7e714d72-664a-4ef3-a679-d678377f3145" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_Settlement2021Member_8a8c3078-b8af-4c1c-aae4-acea5855f468" xlink:href="oxy-20200930.xsd#oxy_Settlement2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f14208f2-1db8-4ba7-9154-e38aed2027c2" xlink:to="loc_oxy_Settlement2021Member_8a8c3078-b8af-4c1c-aae4-acea5855f468" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_95896034-7ac5-4c3a-a872-cdd7290ced01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_2cef2cac-0924-4f3b-8bd4-e9d6def27035" xlink:to="loc_us-gaap_PositionAxis_95896034-7ac5-4c3a-a872-cdd7290ced01" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_95896034-7ac5-4c3a-a872-cdd7290ced01_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_95896034-7ac5-4c3a-a872-cdd7290ced01" xlink:to="loc_us-gaap_PositionDomain_95896034-7ac5-4c3a-a872-cdd7290ced01_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_7fcf2095-b123-462f-b385-106c6e54c977" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_95896034-7ac5-4c3a-a872-cdd7290ced01" xlink:to="loc_us-gaap_PositionDomain_7fcf2095-b123-462f-b385-106c6e54c977" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_5b21fd34-391f-442c-8ae3-3826ebbb4402" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_7fcf2095-b123-462f-b385-106c6e54c977" xlink:to="loc_us-gaap_ShortMember_5b21fd34-391f-442c-8ae3-3826ebbb4402" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_0b254e6d-7b04-428c-9725-39536ed4de5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_7fcf2095-b123-462f-b385-106c6e54c977" xlink:to="loc_us-gaap_LongMember_0b254e6d-7b04-428c-9725-39536ed4de5a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesInterestRateDerivativesDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesInterestRateDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesInterestRateDerivativesDetails" xlink:type="extended" id="i24d66a2009774a31980bf31ab94a661e_DerivativesInterestRateDerivativesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_ae5baaf6-6098-44fa-aa08-6c3abca71d2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:to="loc_us-gaap_DerivativeNotionalAmount_ae5baaf6-6098-44fa-aa08-6c3abca71d2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAverageFixedInterestRate_eeb3c309-df65-49cb-94ff-f222b8c894df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeAverageFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:to="loc_us-gaap_DerivativeAverageFixedInterestRate_eeb3c309-df65-49cb-94ff-f222b8c894df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_6d0e0893-b1f8-4b7f-9fb9-a73f5c1b99cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:to="loc_us-gaap_LongTermDebt_6d0e0893-b1f8-4b7f-9fb9-a73f5c1b99cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromDerivativeInstrumentFinancingActivities_0e1d0260-33c9-4ffe-b6e4-4d3bbf406f35" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsForProceedsFromDerivativeInstrumentFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:to="loc_us-gaap_PaymentsForProceedsFromDerivativeInstrumentFinancingActivities_0e1d0260-33c9-4ffe-b6e4-4d3bbf406f35" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DerivativeInstrumentCollateralReturnedPaid_45ae6c85-1313-4769-b72b-d13f9d77bd84" xlink:href="oxy-20200930.xsd#oxy_DerivativeInstrumentCollateralReturnedPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:to="loc_oxy_DerivativeInstrumentCollateralReturnedPaid_45ae6c85-1313-4769-b72b-d13f9d77bd84" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_866ecdb0-7971-4ebe-8e75-341fcf52fa8a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_82365681-6100-486f-9da9-6bc1af1dd182" xlink:to="loc_us-gaap_DerivativeTable_866ecdb0-7971-4ebe-8e75-341fcf52fa8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_5e99f262-ac6e-4af7-8666-ad00a2411ef0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_866ecdb0-7971-4ebe-8e75-341fcf52fa8a" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_5e99f262-ac6e-4af7-8666-ad00a2411ef0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5e99f262-ac6e-4af7-8666-ad00a2411ef0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_5e99f262-ac6e-4af7-8666-ad00a2411ef0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5e99f262-ac6e-4af7-8666-ad00a2411ef0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_5e99f262-ac6e-4af7-8666-ad00a2411ef0" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20226.835Member_2b70767b-1338-47f9-b17a-121559a67aa8" xlink:href="oxy-20200930.xsd#oxy_InterestRateSwapMandatoryTerminationDateSeptember20226.835Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:to="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20226.835Member_2b70767b-1338-47f9-b17a-121559a67aa8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20206.891Member_4da2db41-a8be-4230-9606-c3fce77bccff" xlink:href="oxy-20200930.xsd#oxy_InterestRateSwapMandatoryTerminationDateSeptember20206.891Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:to="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20206.891Member_4da2db41-a8be-4230-9606-c3fce77bccff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20216.570Member_c385f3a8-5ed0-498b-83a9-9d15f35287a1" xlink:href="oxy-20200930.xsd#oxy_InterestRateSwapMandatoryTerminationDateSeptember20216.570Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:to="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20216.570Member_c385f3a8-5ed0-498b-83a9-9d15f35287a1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20236.445Member_449b43e7-9029-44e6-92c0-d5f07dfb165d" xlink:href="oxy-20200930.xsd#oxy_InterestRateSwapMandatoryTerminationDateSeptember20236.445Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:to="loc_oxy_InterestRateSwapMandatoryTerminationDateSeptember20236.445Member_449b43e7-9029-44e6-92c0-d5f07dfb165d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_45c76606-78b1-4170-b329-3fc33ef7e7f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_52195af9-b7d7-452d-ac93-9b7e83f33478" xlink:to="loc_us-gaap_InterestRateSwapMember_45c76606-78b1-4170-b329-3fc33ef7e7f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_d3a1ae5f-33fd-409a-b61c-97c89d580740" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_866ecdb0-7971-4ebe-8e75-341fcf52fa8a" xlink:to="loc_us-gaap_VariableRateAxis_d3a1ae5f-33fd-409a-b61c-97c89d580740" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_d3a1ae5f-33fd-409a-b61c-97c89d580740_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_d3a1ae5f-33fd-409a-b61c-97c89d580740" xlink:to="loc_us-gaap_VariableRateDomain_d3a1ae5f-33fd-409a-b61c-97c89d580740_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_1c101b6a-7348-497f-9279-b1a64622e1ec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_d3a1ae5f-33fd-409a-b61c-97c89d580740" xlink:to="loc_us-gaap_VariableRateDomain_1c101b6a-7348-497f-9279-b1a64622e1ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_fa00cb68-0501-47c1-8a09-f82bb9b8adaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_1c101b6a-7348-497f-9279-b1a64622e1ec" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_fa00cb68-0501-47c1-8a09-f82bb9b8adaf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesMarketingDerivativesandWarrantsDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesMarketingDerivativesandWarrantsDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesMarketingDerivativesandWarrantsDetails" xlink:type="extended" id="i7651ae7322fa474e984e5b5a5e97ff69_DerivativesMarketingDerivativesandWarrantsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AverageSalesPrices_1ac2ade1-109b-49bb-937f-8ae6fb05c3f0" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_AverageSalesPrices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:to="loc_srt_AverageSalesPrices_1ac2ade1-109b-49bb-937f-8ae6fb05c3f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_78016e11-f410-47e0-be40-531edf06ca67" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountVolume"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountVolume_78016e11-f410-47e0-be40-531edf06ca67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClassOfWarrantOrRightIssued_7e2d4148-d653-4d78-92c6-824c58155cdf" xlink:href="oxy-20200930.xsd#oxy_ClassOfWarrantOrRightIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:to="loc_oxy_ClassOfWarrantOrRightIssued_7e2d4148-d653-4d78-92c6-824c58155cdf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_85c88262-3550-4e6a-a793-a4ad4d5280a2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_85c88262-3550-4e6a-a793-a4ad4d5280a2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClassOfWarrantOrRightFairValue_7c5d57b2-810d-42f6-a750-9e902987c826" xlink:href="oxy-20200930.xsd#oxy_ClassOfWarrantOrRightFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:to="loc_oxy_ClassOfWarrantOrRightFairValue_7c5d57b2-810d-42f6-a750-9e902987c826" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_6a1b3ed4-d03d-4469-967b-d10c787e7629" xlink:to="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6cfaa929-cdbf-461c-9676-c477bf62acdb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6cfaa929-cdbf-461c-9676-c477bf62acdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cfaa929-cdbf-461c-9676-c477bf62acdb_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6cfaa929-cdbf-461c-9676-c477bf62acdb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6cfaa929-cdbf-461c-9676-c477bf62acdb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_40082ecd-4785-4a61-a050-8d18102f9a04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6cfaa929-cdbf-461c-9676-c477bf62acdb" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_40082ecd-4785-4a61-a050-8d18102f9a04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_d991d931-fa29-4378-a5b3-e6812f984f2a" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_40082ecd-4785-4a61-a050-8d18102f9a04" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_d991d931-fa29-4378-a5b3-e6812f984f2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_3b8275f1-e8de-49ed-ba78-518973da9a84" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_3b8275f1-e8de-49ed-ba78-518973da9a84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3b8275f1-e8de-49ed-ba78-518973da9a84_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3b8275f1-e8de-49ed-ba78-518973da9a84" xlink:to="loc_us-gaap_EquityComponentDomain_3b8275f1-e8de-49ed-ba78-518973da9a84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_ccc6498a-bdab-47cc-8f2e-3f37353352dd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3b8275f1-e8de-49ed-ba78-518973da9a84" xlink:to="loc_us-gaap_EquityComponentDomain_ccc6498a-bdab-47cc-8f2e-3f37353352dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_7d48bb5c-e2f2-41f8-843f-f8a442677f08" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ccc6498a-bdab-47cc-8f2e-3f37353352dd" xlink:to="loc_us-gaap_CommonStockMember_7d48bb5c-e2f2-41f8-843f-f8a442677f08" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_c1d5266f-4db6-47b3-87de-2be2beea769e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_ccc6498a-bdab-47cc-8f2e-3f37353352dd" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_c1d5266f-4db6-47b3-87de-2be2beea769e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a5936e09-b6cb-4213-8f09-45386b2ee94b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a5936e09-b6cb-4213-8f09-45386b2ee94b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a5936e09-b6cb-4213-8f09-45386b2ee94b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a5936e09-b6cb-4213-8f09-45386b2ee94b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a5936e09-b6cb-4213-8f09-45386b2ee94b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_21911a5e-bb53-4b1d-8601-fbaa1908ea47" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a5936e09-b6cb-4213-8f09-45386b2ee94b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_21911a5e-bb53-4b1d-8601-fbaa1908ea47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MarketingDerivativesMember_a3bb5400-f201-4c8a-92fd-f938400cff41" xlink:href="oxy-20200930.xsd#oxy_MarketingDerivativesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_21911a5e-bb53-4b1d-8601-fbaa1908ea47" xlink:to="loc_oxy_MarketingDerivativesMember_a3bb5400-f201-4c8a-92fd-f938400cff41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CrudeOilAndNGLPerBarrelMember_6846537e-ba27-4689-bc39-0033666d66df" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CrudeOilAndNGLPerBarrelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_21911a5e-bb53-4b1d-8601-fbaa1908ea47" xlink:to="loc_srt_CrudeOilAndNGLPerBarrelMember_6846537e-ba27-4689-bc39-0033666d66df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_f5bd31d5-080d-4f4f-b11b-a5bbbdbcaf1b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_21911a5e-bb53-4b1d-8601-fbaa1908ea47" xlink:to="loc_us-gaap_WarrantMember_f5bd31d5-080d-4f4f-b11b-a5bbbdbcaf1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_5da601d1-f289-41b1-b137-fbfd293bc860" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:to="loc_us-gaap_HedgingDesignationAxis_5da601d1-f289-41b1-b137-fbfd293bc860" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_5da601d1-f289-41b1-b137-fbfd293bc860_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_5da601d1-f289-41b1-b137-fbfd293bc860" xlink:to="loc_us-gaap_HedgingDesignationDomain_5da601d1-f289-41b1-b137-fbfd293bc860_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_77510a68-cd55-4350-b19e-1a3e6962c8ad" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_5da601d1-f289-41b1-b137-fbfd293bc860" xlink:to="loc_us-gaap_HedgingDesignationDomain_77510a68-cd55-4350-b19e-1a3e6962c8ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_4032ad2a-025e-4010-9440-7fad03ac10e7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_77510a68-cd55-4350-b19e-1a3e6962c8ad" xlink:to="loc_us-gaap_NondesignatedMember_4032ad2a-025e-4010-9440-7fad03ac10e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_3d4b7cc4-46f0-4562-b370-782cff7920f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:to="loc_us-gaap_PositionAxis_3d4b7cc4-46f0-4562-b370-782cff7920f7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_3d4b7cc4-46f0-4562-b370-782cff7920f7_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_3d4b7cc4-46f0-4562-b370-782cff7920f7" xlink:to="loc_us-gaap_PositionDomain_3d4b7cc4-46f0-4562-b370-782cff7920f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_6b20956e-5525-45de-afd2-88824968940d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_3d4b7cc4-46f0-4562-b370-782cff7920f7" xlink:to="loc_us-gaap_PositionDomain_6b20956e-5525-45de-afd2-88824968940d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_4c91e993-1ffe-47d2-af32-8276f6efbba4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_6b20956e-5525-45de-afd2-88824968940d" xlink:to="loc_us-gaap_LongMember_4c91e993-1ffe-47d2-af32-8276f6efbba4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_6beb903b-b4d7-4125-9709-cbe27f60a672" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_6b20956e-5525-45de-afd2-88824968940d" xlink:to="loc_us-gaap_ShortMember_6beb903b-b4d7-4125-9709-cbe27f60a672" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_005b0b51-56c5-439d-9300-b66f709a064c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_015bea99-dbe9-4099-ad2a-cb297b9598ad" xlink:to="loc_srt_StatementScenarioAxis_005b0b51-56c5-439d-9300-b66f709a064c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_005b0b51-56c5-439d-9300-b66f709a064c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_005b0b51-56c5-439d-9300-b66f709a064c" xlink:to="loc_srt_ScenarioUnspecifiedDomain_005b0b51-56c5-439d-9300-b66f709a064c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_717813eb-5399-495b-8512-ded4b5955083" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_005b0b51-56c5-439d-9300-b66f709a064c" xlink:to="loc_srt_ScenarioUnspecifiedDomain_717813eb-5399-495b-8512-ded4b5955083" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScenarioAdjustmentMember_f867433f-411d-4020-953a-12106ea90e2e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScenarioAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_717813eb-5399-495b-8512-ded4b5955083" xlink:to="loc_us-gaap_ScenarioAdjustmentMember_f867433f-411d-4020-953a-12106ea90e2e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesFairValueDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesFairValueDetails" xlink:type="extended" id="i2485fc34dd8d41d0b234ccdcad24d73a_DerivativesFairValueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_a86b13a9-e8c4-4c3a-b5fb-77c27be700a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_a86b13a9-e8c4-4c3a-b5fb-77c27be700a9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_edceb54a-c794-46ae-9961-f7745ec43d7f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset_edceb54a-c794-46ae-9961-f7745ec43d7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_65baf4f9-6d77-4103-86cb-d73e62dbaeba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeAssets_65baf4f9-6d77-4103-86cb-d73e62dbaeba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_70cdfce4-787a-4d51-9a46-669129fba8c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_70cdfce4-787a-4d51-9a46-669129fba8c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_fbb7d4bb-cd3b-4f1d-8114-d92f16295b74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_fbb7d4bb-cd3b-4f1d-8114-d92f16295b74" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_62b6c496-9391-4902-bc96-896939d9ea30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeLiabilities_62b6c496-9391-4902-bc96-896939d9ea30" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_b02507f3-d6de-4243-98d4-3fb97ac84233" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeLiabilityCollateralRightToReclaimCashOffset_b02507f3-d6de-4243-98d4-3fb97ac84233" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCollateralRightToReclaimCash_a6130c0a-57df-4f9f-8e24-c0c62c7ca341" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeCollateralRightToReclaimCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_DerivativeCollateralRightToReclaimCash_a6130c0a-57df-4f9f-8e24-c0c62c7ca341" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarginDepositAssets_00734bd1-2fe0-4119-a01d-66d8064aa430" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MarginDepositAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_MarginDepositAssets_00734bd1-2fe0-4119-a01d-66d8064aa430" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_aeeeae59-189e-4ef2-a5c6-f7d813a03f65" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_04ce3bda-5163-4173-90fe-ad2d97b6d753" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_aeeeae59-189e-4ef2-a5c6-f7d813a03f65" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fc391a48-6868-4878-a312-d48b1d727b9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_aeeeae59-189e-4ef2-a5c6-f7d813a03f65" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fc391a48-6868-4878-a312-d48b1d727b9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fc391a48-6868-4878-a312-d48b1d727b9f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fc391a48-6868-4878-a312-d48b1d727b9f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_fc391a48-6868-4878-a312-d48b1d727b9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7024298b-ff36-4b0b-bd05-bc8aaee3b0d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_fc391a48-6868-4878-a312-d48b1d727b9f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7024298b-ff36-4b0b-bd05-bc8aaee3b0d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_0a6fc6d5-de56-40c0-b99e-1d842ddb4fc9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7024298b-ff36-4b0b-bd05-bc8aaee3b0d3" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_0a6fc6d5-de56-40c0-b99e-1d842ddb4fc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_8876bddf-b852-4829-9b7e-129a069085b3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7024298b-ff36-4b0b-bd05-bc8aaee3b0d3" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_8876bddf-b852-4829-9b7e-129a069085b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_bb4b3e80-9845-40fc-a5e0-f5a2ea881bf3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7024298b-ff36-4b0b-bd05-bc8aaee3b0d3" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_bb4b3e80-9845-40fc-a5e0-f5a2ea881bf3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_3f0c299d-cc62-46f6-95c9-ebd5e022dce0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_aeeeae59-189e-4ef2-a5c6-f7d813a03f65" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_3f0c299d-cc62-46f6-95c9-ebd5e022dce0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3f0c299d-cc62-46f6-95c9-ebd5e022dce0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_3f0c299d-cc62-46f6-95c9-ebd5e022dce0" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3f0c299d-cc62-46f6-95c9-ebd5e022dce0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_116aed3c-6bed-4dd0-9056-064b70fb1fd2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_3f0c299d-cc62-46f6-95c9-ebd5e022dce0" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_116aed3c-6bed-4dd0-9056-064b70fb1fd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_62094b61-dc0d-46c2-921d-cec467b18672" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_116aed3c-6bed-4dd0-9056-064b70fb1fd2" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_62094b61-dc0d-46c2-921d-cec467b18672" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LongTermReceivablesAndOtherAssetsNetMember_55309bed-a0a2-41eb-bfe6-39fefb00f8d2" xlink:href="oxy-20200930.xsd#oxy_LongTermReceivablesAndOtherAssetsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_116aed3c-6bed-4dd0-9056-064b70fb1fd2" xlink:to="loc_oxy_LongTermReceivablesAndOtherAssetsNetMember_55309bed-a0a2-41eb-bfe6-39fefb00f8d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_557dd73f-bd86-459c-85ea-9f81d49fa76e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_116aed3c-6bed-4dd0-9056-064b70fb1fd2" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_557dd73f-bd86-459c-85ea-9f81d49fa76e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DeferredCreditsAndOtherLiabilitiesMember_07c281ba-ff2e-480b-aa36-38ce3f936787" xlink:href="oxy-20200930.xsd#oxy_DeferredCreditsAndOtherLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_116aed3c-6bed-4dd0-9056-064b70fb1fd2" xlink:to="loc_oxy_DeferredCreditsAndOtherLiabilitiesMember_07c281ba-ff2e-480b-aa36-38ce3f936787" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_4175fd1b-fa38-4e5a-be40-011dc47810f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_aeeeae59-189e-4ef2-a5c6-f7d813a03f65" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_4175fd1b-fa38-4e5a-be40-011dc47810f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4175fd1b-fa38-4e5a-be40-011dc47810f1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_4175fd1b-fa38-4e5a-be40-011dc47810f1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4175fd1b-fa38-4e5a-be40-011dc47810f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3ea612f6-6a0d-4ca7-9333-d5e119b1a988" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_4175fd1b-fa38-4e5a-be40-011dc47810f1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3ea612f6-6a0d-4ca7-9333-d5e119b1a988" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilCollarsAndCallsMember_51f2deb9-a3e0-4232-a2d0-eaa35a31df09" xlink:href="oxy-20200930.xsd#oxy_OilCollarsAndCallsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3ea612f6-6a0d-4ca7-9333-d5e119b1a988" xlink:to="loc_oxy_OilCollarsAndCallsMember_51f2deb9-a3e0-4232-a2d0-eaa35a31df09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MarketingDerivativesMember_9d694ac3-6c71-452a-a279-7f6e7405515f" xlink:href="oxy-20200930.xsd#oxy_MarketingDerivativesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3ea612f6-6a0d-4ca7-9333-d5e119b1a988" xlink:to="loc_oxy_MarketingDerivativesMember_9d694ac3-6c71-452a-a279-7f6e7405515f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_54148aa3-dcb6-4fe1-a661-b596602dc958" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3ea612f6-6a0d-4ca7-9333-d5e119b1a988" xlink:to="loc_us-gaap_InterestRateSwapMember_54148aa3-dcb6-4fe1-a661-b596602dc958" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_bf9f2286-a991-4648-9be4-58c626c96104" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3ea612f6-6a0d-4ca7-9333-d5e119b1a988" xlink:to="loc_us-gaap_WarrantMember_bf9f2286-a991-4648-9be4-58c626c96104" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesGainsandLossesonDerivativesDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesGainsandLossesonDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesGainsandLossesonDerivativesDetails" xlink:type="extended" id="i46d89ae8df66475a9a3c656df32ec5d2_DerivativesGainsandLossesonDerivativesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_6ed4c9eb-e2a6-40a0-b3b5-6ea90ba5d34d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_4fa39c4f-f63e-4032-80fd-8e6c4556fc03" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_6ed4c9eb-e2a6-40a0-b3b5-6ea90ba5d34d" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_4fa39c4f-f63e-4032-80fd-8e6c4556fc03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_b576ba0b-2de9-4d29-a3ef-a363d985b5d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_6ed4c9eb-e2a6-40a0-b3b5-6ea90ba5d34d" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_b576ba0b-2de9-4d29-a3ef-a363d985b5d0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_ce41f336-ece3-40af-8c83-f8412642063a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_b576ba0b-2de9-4d29-a3ef-a363d985b5d0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_ce41f336-ece3-40af-8c83-f8412642063a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ce41f336-ece3-40af-8c83-f8412642063a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ce41f336-ece3-40af-8c83-f8412642063a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ce41f336-ece3-40af-8c83-f8412642063a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_28e8e2d0-8267-4f0c-9770-a3b742a4b69d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ce41f336-ece3-40af-8c83-f8412642063a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_28e8e2d0-8267-4f0c-9770-a3b742a4b69d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilCollarsAndCallsMember_907a660e-1bdf-4c07-af28-502b3c75a815" xlink:href="oxy-20200930.xsd#oxy_OilCollarsAndCallsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_28e8e2d0-8267-4f0c-9770-a3b742a4b69d" xlink:to="loc_oxy_OilCollarsAndCallsMember_907a660e-1bdf-4c07-af28-502b3c75a815" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MarketingDerivativesMember_1cefc61e-6a34-48b2-bc38-e2079e7a5229" xlink:href="oxy-20200930.xsd#oxy_MarketingDerivativesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_28e8e2d0-8267-4f0c-9770-a3b742a4b69d" xlink:to="loc_oxy_MarketingDerivativesMember_1cefc61e-6a34-48b2-bc38-e2079e7a5229" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_43b16580-da58-442c-9b37-944d0d7fe9b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_28e8e2d0-8267-4f0c-9770-a3b742a4b69d" xlink:to="loc_us-gaap_InterestRateSwapMember_43b16580-da58-442c-9b37-944d0d7fe9b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_08908c3d-1aac-4039-974a-f5ffd6f3c91e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_28e8e2d0-8267-4f0c-9770-a3b742a4b69d" xlink:to="loc_us-gaap_WarrantMember_08908c3d-1aac-4039-974a-f5ffd6f3c91e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_fe8afa30-5037-4299-ba81-9444231446c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_b576ba0b-2de9-4d29-a3ef-a363d985b5d0" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_fe8afa30-5037-4299-ba81-9444231446c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_fe8afa30-5037-4299-ba81-9444231446c9_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_fe8afa30-5037-4299-ba81-9444231446c9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_fe8afa30-5037-4299-ba81-9444231446c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_00ebbe71-8ab3-45c3-846e-5633d6fb0cf4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_fe8afa30-5037-4299-ba81-9444231446c9" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_00ebbe71-8ab3-45c3-846e-5633d6fb0cf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesMember_dcb92fc1-2248-4b5c-b8d3-75c9dfe7f903" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_00ebbe71-8ab3-45c3-846e-5633d6fb0cf4" xlink:to="loc_us-gaap_SalesMember_dcb92fc1-2248-4b5c-b8d3-75c9dfe7f903" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GainLossonInterestRateSwapsandWarrantsNetMember_f1e3e04b-0794-446f-8e07-aadb4283e797" xlink:href="oxy-20200930.xsd#oxy_GainLossonInterestRateSwapsandWarrantsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_00ebbe71-8ab3-45c3-846e-5633d6fb0cf4" xlink:to="loc_oxy_GainLossonInterestRateSwapsandWarrantsNetMember_f1e3e04b-0794-446f-8e07-aadb4283e797" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f2e963d5-2386-485d-8a44-a8c2905493dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_b576ba0b-2de9-4d29-a3ef-a363d985b5d0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f2e963d5-2386-485d-8a44-a8c2905493dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f2e963d5-2386-485d-8a44-a8c2905493dc_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f2e963d5-2386-485d-8a44-a8c2905493dc" xlink:to="loc_us-gaap_SegmentDomain_f2e963d5-2386-485d-8a44-a8c2905493dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_88a59a3a-036f-421c-a4b3-ea9a7e1696bf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f2e963d5-2386-485d-8a44-a8c2905493dc" xlink:to="loc_us-gaap_SegmentDomain_88a59a3a-036f-421c-a4b3-ea9a7e1696bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_WesternMidstreamPartnersLPMember_30d346f3-a058-4406-a2d2-a802b6f5458f" xlink:href="oxy-20200930.xsd#oxy_WesternMidstreamPartnersLPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_88a59a3a-036f-421c-a4b3-ea9a7e1696bf" xlink:to="loc_oxy_WesternMidstreamPartnersLPMember_30d346f3-a058-4406-a2d2-a802b6f5458f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/DerivativesCreditRiskDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#DerivativesCreditRiskDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/DerivativesCreditRiskDetails" xlink:type="extended" id="ibfa2d2043d404ebb9a202c990d5671d9_DerivativesCreditRiskDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_6e0ce82a-92ac-49a3-91b9-b81313037209" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNetLiabilityPositionAggregateFairValue_c819e97b-b40c-4ac2-9e6a-fc665d520a88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNetLiabilityPositionAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6e0ce82a-92ac-49a3-91b9-b81313037209" xlink:to="loc_us-gaap_DerivativeNetLiabilityPositionAggregateFairValue_c819e97b-b40c-4ac2-9e6a-fc665d520a88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollateralAlreadyPostedAggregateFairValue_953b14dc-8d43-469f-97f2-86eff162961b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CollateralAlreadyPostedAggregateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_6e0ce82a-92ac-49a3-91b9-b81313037209" xlink:to="loc_us-gaap_CollateralAlreadyPostedAggregateFairValue_953b14dc-8d43-469f-97f2-86eff162961b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_3c66afc8-5915-4313-8fe4-0eb4e9b40bfd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_6e0ce82a-92ac-49a3-91b9-b81313037209" xlink:to="loc_us-gaap_DerivativeTable_3c66afc8-5915-4313-8fe4-0eb4e9b40bfd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_ec267559-f8bf-40fc-bffe-668550cf6380" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3c66afc8-5915-4313-8fe4-0eb4e9b40bfd" xlink:to="loc_us-gaap_HedgingDesignationAxis_ec267559-f8bf-40fc-bffe-668550cf6380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ec267559-f8bf-40fc-bffe-668550cf6380_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_ec267559-f8bf-40fc-bffe-668550cf6380" xlink:to="loc_us-gaap_HedgingDesignationDomain_ec267559-f8bf-40fc-bffe-668550cf6380_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_9c119f57-3418-4840-a68a-1e34884384c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_ec267559-f8bf-40fc-bffe-668550cf6380" xlink:to="loc_us-gaap_HedgingDesignationDomain_9c119f57-3418-4840-a68a-1e34884384c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_9a6df750-6a77-4380-9567-ad5441db3002" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_9c119f57-3418-4840-a68a-1e34884384c0" xlink:to="loc_us-gaap_NondesignatedMember_9a6df750-6a77-4380-9567-ad5441db3002" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_cd6cc0c0-17cf-420a-bd8b-69ba3c719fb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_3c66afc8-5915-4313-8fe4-0eb4e9b40bfd" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_cd6cc0c0-17cf-420a-bd8b-69ba3c719fb8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_cd6cc0c0-17cf-420a-bd8b-69ba3c719fb8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_cd6cc0c0-17cf-420a-bd8b-69ba3c719fb8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_cd6cc0c0-17cf-420a-bd8b-69ba3c719fb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_752510c2-515c-499b-a1e0-2d0454ca6b1c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_cd6cc0c0-17cf-420a-bd8b-69ba3c719fb8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_752510c2-515c-499b-a1e0-2d0454ca6b1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MarketingDerivativesMember_9e2a6fec-c5f4-4201-8558-ef91f2053d28" xlink:href="oxy-20200930.xsd#oxy_MarketingDerivativesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_752510c2-515c-499b-a1e0-2d0454ca6b1c" xlink:to="loc_oxy_MarketingDerivativesMember_9e2a6fec-c5f4-4201-8558-ef91f2053d28" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/FairValueMeasurements" xlink:type="simple" xlink:href="oxy-20200930.xsd#FairValueMeasurements"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/FairValueMeasurements" xlink:type="extended" id="iac00a9dc09cc4f2787b8c11ba76e4983_FairValueMeasurements"/>
  <link:roleRef roleURI="http://www.oxy.com/role/FairValueMeasurementsTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#FairValueMeasurementsTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/FairValueMeasurementsTables" xlink:type="extended" id="i1fbf9ef67f7743ed94b41c27cde61d4e_FairValueMeasurementsTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/FairValueMeasurementsDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#FairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/FairValueMeasurementsDetails" xlink:type="extended" id="ia7da55169883409ab6051a8d860b49ac_FairValueMeasurementsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_4c9f5c6e-d3be-4fa3-a52e-0526f794eba8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_4c9f5c6e-d3be-4fa3-a52e-0526f794eba8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability_7a6a7b29-2c0d-48ec-9d6a-7c93a40c78b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_4c9f5c6e-d3be-4fa3-a52e-0526f794eba8" xlink:to="loc_us-gaap_EmbeddedDerivativeFairValueOfEmbeddedDerivativeLiability_7a6a7b29-2c0d-48ec-9d6a-7c93a40c78b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_83a6e4aa-b7e9-421f-a316-343ee0bd0b36" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_4c9f5c6e-d3be-4fa3-a52e-0526f794eba8" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset_83a6e4aa-b7e9-421f-a316-343ee0bd0b36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_02055676-8e6c-4c80-9959-d1f73e4d0ab4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_us-gaap_AssetImpairmentCharges_02055676-8e6c-4c80-9959-d1f73e4d0ab4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AssetImpairmentChargesNetOfTax_db1771ee-a09e-451c-a0c1-56dc5695643e" xlink:href="oxy-20200930.xsd#oxy_AssetImpairmentChargesNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_oxy_AssetImpairmentChargesNetOfTax_db1771ee-a09e-451c-a0c1-56dc5695643e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilandGasPropertiesMeasurementInput_c0ddeb47-fa70-41ad-b356-b7d30d1d67e2" xlink:href="oxy-20200930.xsd#oxy_OilandGasPropertiesMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_oxy_OilandGasPropertiesMeasurementInput_c0ddeb47-fa70-41ad-b356-b7d30d1d67e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AverageSalesPrices_427a0331-9cb5-4e49-bacc-489acbb02ca3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_AverageSalesPrices"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_srt_AverageSalesPrices_427a0331-9cb5-4e49-bacc-489acbb02ca3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasUnweightedArithmeticAverageSalePrice_c8a41c9e-086e-4f0d-b036-92e92c76f0b2" xlink:href="oxy-20200930.xsd#oxy_OilAndGasUnweightedArithmeticAverageSalePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_oxy_OilAndGasUnweightedArithmeticAverageSalePrice_c8a41c9e-086e-4f0d-b036-92e92c76f0b2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasUnweightedArithmeticAveragePricePeriod_9491c5c4-14f3-476d-bbb8-d5b980f16ec0" xlink:href="oxy-20200930.xsd#oxy_OilAndGasUnweightedArithmeticAveragePricePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_oxy_OilAndGasUnweightedArithmeticAveragePricePeriod_9491c5c4-14f3-476d-bbb8-d5b980f16ec0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasOperatingAndCapitalCostEstimatesPercentage_0f49c7c8-cb97-4ce0-b41e-c5083397b713" xlink:href="oxy-20200930.xsd#oxy_OilAndGasOperatingAndCapitalCostEstimatesPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_oxy_OilAndGasOperatingAndCapitalCostEstimatesPercentage_0f49c7c8-cb97-4ce0-b41e-c5083397b713" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasOperatingAndCapitalCostEstimates_c58b7e3b-5637-4957-ba80-30d4bf038e7e" xlink:href="oxy-20200930.xsd#oxy_OilAndGasOperatingAndCapitalCostEstimates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_oxy_OilAndGasOperatingAndCapitalCostEstimates_c58b7e3b-5637-4957-ba80-30d4bf038e7e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_3185a7a6-fe40-41fd-aa45-cc8eed3fc998" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_us-gaap_Goodwill_3185a7a6-fe40-41fd-aa45-cc8eed3fc998" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_3843f0cb-ea4e-4cab-9544-c6843688c468" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_3843f0cb-ea4e-4cab-9544-c6843688c468" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7b9d567e-0d79-4fe2-b54b-9762f0eb1d48" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f71962fe-3929-4df0-86f6-d8cda7b656a5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f71962fe-3929-4df0-86f6-d8cda7b656a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f71962fe-3929-4df0-86f6-d8cda7b656a5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f71962fe-3929-4df0-86f6-d8cda7b656a5" xlink:to="loc_us-gaap_SegmentDomain_f71962fe-3929-4df0-86f6-d8cda7b656a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a0f4d54a-a7e0-4e5c-ae69-4a7357d6c835" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f71962fe-3929-4df0-86f6-d8cda7b656a5" xlink:to="loc_us-gaap_SegmentDomain_a0f4d54a-a7e0-4e5c-ae69-4a7357d6c835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasSegmentMember_c93ef85f-35b8-4304-ae18-2a4b316d6541" xlink:href="oxy-20200930.xsd#oxy_OilAndGasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a0f4d54a-a7e0-4e5c-ae69-4a7357d6c835" xlink:to="loc_oxy_OilAndGasSegmentMember_c93ef85f-35b8-4304-ae18-2a4b316d6541" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MidstreamAndMarketingMember_607952c6-250c-413e-9efe-71e7120be322" xlink:href="oxy-20200930.xsd#oxy_MidstreamAndMarketingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a0f4d54a-a7e0-4e5c-ae69-4a7357d6c835" xlink:to="loc_oxy_MidstreamAndMarketingMember_607952c6-250c-413e-9efe-71e7120be322" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_611b425e-67ac-400f-8c1e-9e18715aa1b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_611b425e-67ac-400f-8c1e-9e18715aa1b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_611b425e-67ac-400f-8c1e-9e18715aa1b1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_611b425e-67ac-400f-8c1e-9e18715aa1b1" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_611b425e-67ac-400f-8c1e-9e18715aa1b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4192dada-9874-473a-b725-268b4df4d740" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_611b425e-67ac-400f-8c1e-9e18715aa1b1" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4192dada-9874-473a-b725-268b4df4d740" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GhanaAssetsMember_846710bc-75b1-4002-a158-baf8dfbf28bc" xlink:href="oxy-20200930.xsd#oxy_GhanaAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_4192dada-9874-473a-b725-268b4df4d740" xlink:to="loc_oxy_GhanaAssetsMember_846710bc-75b1-4002-a158-baf8dfbf28bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_0262aab0-8f59-4932-af65-7b00ef772c9e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_0262aab0-8f59-4932-af65-7b00ef772c9e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_0262aab0-8f59-4932-af65-7b00ef772c9e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_0262aab0-8f59-4932-af65-7b00ef772c9e" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_0262aab0-8f59-4932-af65-7b00ef772c9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_0456d5f2-c6fc-4ae1-96ef-83f6fa271781" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_0262aab0-8f59-4932-af65-7b00ef772c9e" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_0456d5f2-c6fc-4ae1-96ef-83f6fa271781" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_06c6d92e-6251-41ed-954b-4674f61a7ddc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_0456d5f2-c6fc-4ae1-96ef-83f6fa271781" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_06c6d92e-6251-41ed-954b-4674f61a7ddc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e2e1940-3129-4a72-9cc0-b08f642ba691" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e2e1940-3129-4a72-9cc0-b08f642ba691" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_8e2e1940-3129-4a72-9cc0-b08f642ba691_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e2e1940-3129-4a72-9cc0-b08f642ba691" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_8e2e1940-3129-4a72-9cc0-b08f642ba691_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_f5b4fc63-ca2e-4a66-8336-338deb54385d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8e2e1940-3129-4a72-9cc0-b08f642ba691" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_f5b4fc63-ca2e-4a66-8336-338deb54385d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_9da24823-bd7a-4ba6-992e-33fb973f8099" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_f5b4fc63-ca2e-4a66-8336-338deb54385d" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_9da24823-bd7a-4ba6-992e-33fb973f8099" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_0aaf088b-fe9c-423e-9435-852ea83b21cf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_0aaf088b-fe9c-423e-9435-852ea83b21cf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_0aaf088b-fe9c-423e-9435-852ea83b21cf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_0aaf088b-fe9c-423e-9435-852ea83b21cf" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_0aaf088b-fe9c-423e-9435-852ea83b21cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_5007430f-7f55-4ac3-b3fc-a2cb0c3d4fe3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_0aaf088b-fe9c-423e-9435-852ea83b21cf" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_5007430f-7f55-4ac3-b3fc-a2cb0c3d4fe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_e253f293-99ab-45e3-b22f-16eb4a2b5e3f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_5007430f-7f55-4ac3-b3fc-a2cb0c3d4fe3" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_e253f293-99ab-45e3-b22f-16eb4a2b5e3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DeferredCreditsAndOtherLiabilitiesMember_ed6f3647-4b69-46c9-bc7d-48170d95be16" xlink:href="oxy-20200930.xsd#oxy_DeferredCreditsAndOtherLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_5007430f-7f55-4ac3-b3fc-a2cb0c3d4fe3" xlink:to="loc_oxy_DeferredCreditsAndOtherLiabilitiesMember_ed6f3647-4b69-46c9-bc7d-48170d95be16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8a68b6ad-6616-4086-a5e1-ae52b77f6444" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8a68b6ad-6616-4086-a5e1-ae52b77f6444" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8a68b6ad-6616-4086-a5e1-ae52b77f6444_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8a68b6ad-6616-4086-a5e1-ae52b77f6444" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_8a68b6ad-6616-4086-a5e1-ae52b77f6444_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bcc84954-601f-45d6-b6d8-32e721bef6c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_8a68b6ad-6616-4086-a5e1-ae52b77f6444" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bcc84954-601f-45d6-b6d8-32e721bef6c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_65dcb144-0b87-4476-9269-1cf2f8f908d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bcc84954-601f-45d6-b6d8-32e721bef6c4" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_65dcb144-0b87-4476-9269-1cf2f8f908d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_ea957f36-2880-4895-a23c-2ec8d7112741" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bcc84954-601f-45d6-b6d8-32e721bef6c4" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_ea957f36-2880-4895-a23c-2ec8d7112741" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_ef35de83-fcea-4e11-956a-4400ca1227cc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bcc84954-601f-45d6-b6d8-32e721bef6c4" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_ef35de83-fcea-4e11-956a-4400ca1227cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_d95677c9-836d-4b98-baea-2fd63a8ea444" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_d95677c9-836d-4b98-baea-2fd63a8ea444" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d95677c9-836d-4b98-baea-2fd63a8ea444_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_d95677c9-836d-4b98-baea-2fd63a8ea444" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_d95677c9-836d-4b98-baea-2fd63a8ea444_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2f96f72e-634c-4ae4-8e64-6ead5db83716" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_d95677c9-836d-4b98-baea-2fd63a8ea444" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2f96f72e-634c-4ae4-8e64-6ead5db83716" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1a91ace8-9792-4439-ad85-f7bf88ad8593" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2f96f72e-634c-4ae4-8e64-6ead5db83716" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_1a91ace8-9792-4439-ad85-f7bf88ad8593" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_73ee9919-8525-40ac-b320-0d4bc769951e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2f96f72e-634c-4ae4-8e64-6ead5db83716" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_73ee9919-8525-40ac-b320-0d4bc769951e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_b633b108-040f-4949-bd08-fb75f1d21207" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_srt_StatementGeographicalAxis_b633b108-040f-4949-bd08-fb75f1d21207" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b633b108-040f-4949-bd08-fb75f1d21207_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_b633b108-040f-4949-bd08-fb75f1d21207" xlink:to="loc_srt_SegmentGeographicalDomain_b633b108-040f-4949-bd08-fb75f1d21207_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_d2f7f329-5952-4cc4-830d-037e05c0c246" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_b633b108-040f-4949-bd08-fb75f1d21207" xlink:to="loc_srt_SegmentGeographicalDomain_d2f7f329-5952-4cc4-830d-037e05c0c246" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OmanBoliviaAndTheGulfOfMexicoMember_674323b1-b709-4fb3-887a-611efeacf6ca" xlink:href="oxy-20200930.xsd#oxy_OmanBoliviaAndTheGulfOfMexicoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d2f7f329-5952-4cc4-830d-037e05c0c246" xlink:to="loc_oxy_OmanBoliviaAndTheGulfOfMexicoMember_674323b1-b709-4fb3-887a-611efeacf6ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_GulfOfMexicoMember_25595bc1-90f7-462e-81b1-475cc66a0a89" xlink:href="oxy-20200930.xsd#oxy_GulfOfMexicoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d2f7f329-5952-4cc4-830d-037e05c0c246" xlink:to="loc_oxy_GulfOfMexicoMember_25595bc1-90f7-462e-81b1-475cc66a0a89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AlgeriaOilAndGasProvedPropertiesMember_b37357f0-6f6f-4063-a734-f5ec7cda0a15" xlink:href="oxy-20200930.xsd#oxy_AlgeriaOilAndGasProvedPropertiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d2f7f329-5952-4cc4-830d-037e05c0c246" xlink:to="loc_oxy_AlgeriaOilAndGasProvedPropertiesMember_b37357f0-6f6f-4063-a734-f5ec7cda0a15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DomesticOnshoreUnprovedAcreageMember_af754165-33a3-460e-9c46-29ee79e15e8d" xlink:href="oxy-20200930.xsd#oxy_DomesticOnshoreUnprovedAcreageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_d2f7f329-5952-4cc4-830d-037e05c0c246" xlink:to="loc_oxy_DomesticOnshoreUnprovedAcreageMember_af754165-33a3-460e-9c46-29ee79e15e8d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_d4467b0a-162f-4685-a0cc-5cea4143e623" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_d4467b0a-162f-4685-a0cc-5cea4143e623" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_d4467b0a-162f-4685-a0cc-5cea4143e623_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_d4467b0a-162f-4685-a0cc-5cea4143e623" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_d4467b0a-162f-4685-a0cc-5cea4143e623_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_d1883051-1c78-4507-a816-ddd3648897ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_d4467b0a-162f-4685-a0cc-5cea4143e623" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_d1883051-1c78-4507-a816-ddd3648897ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MeasurementInputWeightedAverageCostOfCapitalMember_2febd3f2-88b6-4841-81e9-616cbe02933e" xlink:href="oxy-20200930.xsd#oxy_MeasurementInputWeightedAverageCostOfCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_d1883051-1c78-4507-a816-ddd3648897ff" xlink:to="loc_oxy_MeasurementInputWeightedAverageCostOfCapitalMember_2febd3f2-88b6-4841-81e9-616cbe02933e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6fa1352f-f2bb-4a14-a0bd-452bbf4dd902" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6fa1352f-f2bb-4a14-a0bd-452bbf4dd902" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6fa1352f-f2bb-4a14-a0bd-452bbf4dd902_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6fa1352f-f2bb-4a14-a0bd-452bbf4dd902" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6fa1352f-f2bb-4a14-a0bd-452bbf4dd902_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe99631e-1376-4cda-9f5b-f31b5d2f2c2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6fa1352f-f2bb-4a14-a0bd-452bbf4dd902" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe99631e-1376-4cda-9f5b-f31b5d2f2c2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_d939515a-3e97-4bed-abf1-234c40a8d499" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe99631e-1376-4cda-9f5b-f31b5d2f2c2d" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_d939515a-3e97-4bed-abf1-234c40a8d499" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyAxis_984c862e-8c4b-4214-be09-a4a51166cbaf" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EnergyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_srt_EnergyAxis_984c862e-8c4b-4214-be09-a4a51166cbaf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_984c862e-8c4b-4214-be09-a4a51166cbaf_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_EnergyAxis_984c862e-8c4b-4214-be09-a4a51166cbaf" xlink:to="loc_srt_EnergyDomain_984c862e-8c4b-4214-be09-a4a51166cbaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EnergyDomain_67a6616c-56b5-4101-858b-8e3aedb7d50d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_EnergyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_EnergyAxis_984c862e-8c4b-4214-be09-a4a51166cbaf" xlink:to="loc_srt_EnergyDomain_67a6616c-56b5-4101-858b-8e3aedb7d50d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CrudeOilMember_7fd805ec-4dbd-469f-ad02-73bd96306a06" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CrudeOilMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_67a6616c-56b5-4101-858b-8e3aedb7d50d" xlink:to="loc_srt_CrudeOilMember_7fd805ec-4dbd-469f-ad02-73bd96306a06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NaturalGasReservesMember_2012fe78-2699-4741-96dd-f7cbf8dd5262" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NaturalGasReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EnergyDomain_67a6616c-56b5-4101-858b-8e3aedb7d50d" xlink:to="loc_srt_NaturalGasReservesMember_2012fe78-2699-4741-96dd-f7cbf8dd5262" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_24dd0d3d-6f62-4c20-b234-7a3c0f6598fa" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_af0f48eb-dba5-4cf6-a2dc-596a292c1eae" xlink:to="loc_srt_RangeAxis_24dd0d3d-6f62-4c20-b234-7a3c0f6598fa" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_24dd0d3d-6f62-4c20-b234-7a3c0f6598fa_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_24dd0d3d-6f62-4c20-b234-7a3c0f6598fa" xlink:to="loc_srt_RangeMember_24dd0d3d-6f62-4c20-b234-7a3c0f6598fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_773a13ab-5fca-4098-962a-90a14af78a1d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_24dd0d3d-6f62-4c20-b234-7a3c0f6598fa" xlink:to="loc_srt_RangeMember_773a13ab-5fca-4098-962a-90a14af78a1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5eed77d3-f4f6-4663-8087-1e8b01aecb1f" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_773a13ab-5fca-4098-962a-90a14af78a1d" xlink:to="loc_srt_MinimumMember_5eed77d3-f4f6-4663-8087-1e8b01aecb1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_4eb7ece1-da49-4d25-be70-a28354f97d07" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_773a13ab-5fca-4098-962a-90a14af78a1d" xlink:to="loc_srt_MaximumMember_4eb7ece1-da49-4d25-be70-a28354f97d07" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/LongTermDebt" xlink:type="simple" xlink:href="oxy-20200930.xsd#LongTermDebt"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LongTermDebt" xlink:type="extended" id="i6b0cb9626a134b618b344937cf261a32_LongTermDebt"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LongTermDebtTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#LongTermDebtTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LongTermDebtTables" xlink:type="extended" id="i7f823e02c3e9451f94724002b47ee123_LongTermDebtTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LongTermDebtScheduleofLongtermDebtDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LongTermDebtScheduleofLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LongTermDebtScheduleofLongtermDebtDetails" xlink:type="extended" id="i32b4f84da8914afa95f44f393da59c54_LongTermDebtScheduleofLongtermDebtDetails"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LongTermDebtNarrativeDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LongTermDebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LongTermDebtNarrativeDetails" xlink:type="extended" id="ie16526eb85984e6680e3f163da0fd325_LongTermDebtNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_cf4df25a-5ec5-4f98-88c3-91911fcce361" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_us-gaap_DebtInstrumentTerm_cf4df25a-5ec5-4f98-88c3-91911fcce361" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_RelatedPartiesCommonUnitsIssuedInNotesPayableRetirement_5ffb9df3-4de9-49d3-956c-517125c69cd6" xlink:href="oxy-20200930.xsd#oxy_RelatedPartiesCommonUnitsIssuedInNotesPayableRetirement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_oxy_RelatedPartiesCommonUnitsIssuedInNotesPayableRetirement_5ffb9df3-4de9-49d3-956c-517125c69cd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_NotesPayableRelatedPartiesAmountRetired_27713284-903e-427d-bc97-62f82d2e6d7b" xlink:href="oxy-20200930.xsd#oxy_NotesPayableRelatedPartiesAmountRetired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_oxy_NotesPayableRelatedPartiesAmountRetired_27713284-903e-427d-bc97-62f82d2e6d7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_NotesPayableRelatedPartiesGainLossOnExchange_4b7cba39-7ae7-47a7-97cb-1b04f67a542b" xlink:href="oxy-20200930.xsd#oxy_NotesPayableRelatedPartiesGainLossOnExchange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_oxy_NotesPayableRelatedPartiesGainLossOnExchange_4b7cba39-7ae7-47a7-97cb-1b04f67a542b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_1cc3b1f2-eeed-488b-a3e9-b699c3dc6778" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_1cc3b1f2-eeed-488b-a3e9-b699c3dc6778" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_210150b0-8f2f-4a61-b8a9-fc525df71c22" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_us-gaap_RepaymentsOfDebt_210150b0-8f2f-4a61-b8a9-fc525df71c22" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayable_ab48da8d-189a-4801-a811-eef7de1e1c74" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_us-gaap_NotesPayable_ab48da8d-189a-4801-a811-eef7de1e1c74" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_6a8282bc-60d8-4ab7-9a7f-1c39d89142e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_us-gaap_DebtInstrumentFairValue_6a8282bc-60d8-4ab7-9a7f-1c39d89142e9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7bafabb5-58b1-480c-9526-4e5a7464c8c0" xlink:to="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_73f789ee-b571-4d82-9de4-7c7de8b24a50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_73f789ee-b571-4d82-9de4-7c7de8b24a50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_73f789ee-b571-4d82-9de4-7c7de8b24a50_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_73f789ee-b571-4d82-9de4-7c7de8b24a50" xlink:to="loc_us-gaap_RelatedPartyDomain_73f789ee-b571-4d82-9de4-7c7de8b24a50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_a0e71940-92a8-4034-ab4d-a4ad05621053" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_73f789ee-b571-4d82-9de4-7c7de8b24a50" xlink:to="loc_us-gaap_RelatedPartyDomain_a0e71940-92a8-4034-ab4d-a4ad05621053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_c7070b95-fe32-4a60-9237-4cd05b7fd2c9" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_a0e71940-92a8-4034-ab4d-a4ad05621053" xlink:to="loc_srt_AffiliatedEntityMember_c7070b95-fe32-4a60-9237-4cd05b7fd2c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ed57e827-1b8e-4df0-83c0-55886544f413" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_srt_RangeAxis_ed57e827-1b8e-4df0-83c0-55886544f413" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ed57e827-1b8e-4df0-83c0-55886544f413_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ed57e827-1b8e-4df0-83c0-55886544f413" xlink:to="loc_srt_RangeMember_ed57e827-1b8e-4df0-83c0-55886544f413_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a291080b-2084-4171-8288-a21d75e0f0ba" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ed57e827-1b8e-4df0-83c0-55886544f413" xlink:to="loc_srt_RangeMember_a291080b-2084-4171-8288-a21d75e0f0ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_17645141-28f8-4b7c-a819-c300801854b3" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a291080b-2084-4171-8288-a21d75e0f0ba" xlink:to="loc_srt_MinimumMember_17645141-28f8-4b7c-a819-c300801854b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_7902d59d-f556-476e-a841-481e20f36a1c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a291080b-2084-4171-8288-a21d75e0f0ba" xlink:to="loc_srt_MaximumMember_7902d59d-f556-476e-a841-481e20f36a1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DebtInstrumentPeriodAxis_b4964b8a-b216-4e36-961a-e74e249a58b5" xlink:href="oxy-20200930.xsd#oxy_DebtInstrumentPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_oxy_DebtInstrumentPeriodAxis_b4964b8a-b216-4e36-961a-e74e249a58b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DebtInstrumentPeriodDomain_b4964b8a-b216-4e36-961a-e74e249a58b5_default" xlink:href="oxy-20200930.xsd#oxy_DebtInstrumentPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_oxy_DebtInstrumentPeriodAxis_b4964b8a-b216-4e36-961a-e74e249a58b5" xlink:to="loc_oxy_DebtInstrumentPeriodDomain_b4964b8a-b216-4e36-961a-e74e249a58b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DebtInstrumentPeriodDomain_5800157d-4ab4-4056-a857-ce45a542f88e" xlink:href="oxy-20200930.xsd#oxy_DebtInstrumentPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_oxy_DebtInstrumentPeriodAxis_b4964b8a-b216-4e36-961a-e74e249a58b5" xlink:to="loc_oxy_DebtInstrumentPeriodDomain_5800157d-4ab4-4056-a857-ce45a542f88e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_IssuanceOfJulyAndAugust2020NotesMember_3ca3f980-752d-408b-9c45-8b21596fa287" xlink:href="oxy-20200930.xsd#oxy_IssuanceOfJulyAndAugust2020NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_5800157d-4ab4-4056-a857-ce45a542f88e" xlink:to="loc_oxy_IssuanceOfJulyAndAugust2020NotesMember_3ca3f980-752d-408b-9c45-8b21596fa287" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_TenderOffersJulyAndAugust2020Member_19459339-cfca-402f-a43e-7cbb8fe48736" xlink:href="oxy-20200930.xsd#oxy_TenderOffersJulyAndAugust2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_5800157d-4ab4-4056-a857-ce45a542f88e" xlink:to="loc_oxy_TenderOffersJulyAndAugust2020Member_19459339-cfca-402f-a43e-7cbb8fe48736" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_a0611c42-5d65-4d8e-ab42-71ab57e94057" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_a0611c42-5d65-4d8e-ab42-71ab57e94057" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_a0611c42-5d65-4d8e-ab42-71ab57e94057_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a0611c42-5d65-4d8e-ab42-71ab57e94057" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_a0611c42-5d65-4d8e-ab42-71ab57e94057_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_71ad59eb-47d1-4218-88bd-3324ec7cafca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a0611c42-5d65-4d8e-ab42-71ab57e94057" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_71ad59eb-47d1-4218-88bd-3324ec7cafca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_6c2fbfa1-e2a8-4c78-a5a1-3e69175c9ac5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_71ad59eb-47d1-4218-88bd-3324ec7cafca" xlink:to="loc_us-gaap_SeniorNotesMember_6c2fbfa1-e2a8-4c78-a5a1-3e69175c9ac5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_9ddaba2d-0fdf-4b46-98d4-e31e52a71e4d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_us-gaap_DebtInstrumentAxis_9ddaba2d-0fdf-4b46-98d4-e31e52a71e4d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_9ddaba2d-0fdf-4b46-98d4-e31e52a71e4d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_9ddaba2d-0fdf-4b46-98d4-e31e52a71e4d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_9ddaba2d-0fdf-4b46-98d4-e31e52a71e4d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cd951a0e-ce18-4edd-a068-868d52565f39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_9ddaba2d-0fdf-4b46-98d4-e31e52a71e4d" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cd951a0e-ce18-4edd-a068-868d52565f39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_VariableRateBondsDue2021Member_6b7e96ba-ea11-464f-a64e-a340fb69497a" xlink:href="oxy-20200930.xsd#oxy_VariableRateBondsDue2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cd951a0e-ce18-4edd-a068-868d52565f39" xlink:to="loc_oxy_VariableRateBondsDue2021Member_6b7e96ba-ea11-464f-a64e-a340fb69497a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_VariableRateTermLoanDue2021Member_56119bce-917b-4b59-9564-eca1dfba199c" xlink:href="oxy-20200930.xsd#oxy_VariableRateTermLoanDue2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cd951a0e-ce18-4edd-a068-868d52565f39" xlink:to="loc_oxy_VariableRateTermLoanDue2021Member_56119bce-917b-4b59-9564-eca1dfba199c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_3012d7ed-c06f-459a-931d-2a2748fe6cdd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_3012d7ed-c06f-459a-931d-2a2748fe6cdd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_3012d7ed-c06f-459a-931d-2a2748fe6cdd_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_3012d7ed-c06f-459a-931d-2a2748fe6cdd" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_3012d7ed-c06f-459a-931d-2a2748fe6cdd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_0066e3ca-cf01-49ad-975e-7ca22429c5af" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_3012d7ed-c06f-459a-931d-2a2748fe6cdd" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_0066e3ca-cf01-49ad-975e-7ca22429c5af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_379856b7-6331-4604-bd93-b29b683a17a4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_0066e3ca-cf01-49ad-975e-7ca22429c5af" xlink:to="loc_us-gaap_SubsequentEventMember_379856b7-6331-4604-bd93-b29b683a17a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_ded4e964-e4df-47bb-94ee-89b9a10a2a7d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_ded4e964-e4df-47bb-94ee-89b9a10a2a7d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_ded4e964-e4df-47bb-94ee-89b9a10a2a7d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_ded4e964-e4df-47bb-94ee-89b9a10a2a7d" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_ded4e964-e4df-47bb-94ee-89b9a10a2a7d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e45df500-21a7-438c-9aeb-14ad5e0b7581" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_ded4e964-e4df-47bb-94ee-89b9a10a2a7d" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e45df500-21a7-438c-9aeb-14ad5e0b7581" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a2ca0bba-e2ea-4516-a6d8-3840b16d60a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e45df500-21a7-438c-9aeb-14ad5e0b7581" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_a2ca0bba-e2ea-4516-a6d8-3840b16d60a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_a195d78e-0db8-4327-a88f-e8e1a1a4d343" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_e45df500-21a7-438c-9aeb-14ad5e0b7581" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_a195d78e-0db8-4327-a88f-e8e1a1a4d343" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3f3d8546-de9f-47f5-a4cc-a30c28d57063" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_41d644c6-0193-490a-a43b-5ab2a4890d89" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3f3d8546-de9f-47f5-a4cc-a30c28d57063" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3f3d8546-de9f-47f5-a4cc-a30c28d57063_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3f3d8546-de9f-47f5-a4cc-a30c28d57063" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_3f3d8546-de9f-47f5-a4cc-a30c28d57063_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b66d1ac8-d7a5-4d37-b0b9-13d9f2f45ae9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_3f3d8546-de9f-47f5-a4cc-a30c28d57063" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b66d1ac8-d7a5-4d37-b0b9-13d9f2f45ae9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_97308000-1b72-4cf7-97a0-f6b57a0eeee9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b66d1ac8-d7a5-4d37-b0b9-13d9f2f45ae9" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_97308000-1b72-4cf7-97a0-f6b57a0eeee9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/LongTermDebtDebtIssuanceRepurchasesRepaymentsandExchangesDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LongTermDebtDebtIssuanceRepurchasesRepaymentsandExchangesDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LongTermDebtDebtIssuanceRepurchasesRepaymentsandExchangesDetails" xlink:type="extended" id="if253a2db23be4c50885dc321327192ca_LongTermDebtDebtIssuanceRepurchasesRepaymentsandExchangesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_7575ee23-3cd9-4482-98a5-1bd802a6ca61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_LongTermDebtRollforwardRollForward_b82be371-deb2-4e05-a53d-50481cdafce4" xlink:href="oxy-20200930.xsd#oxy_LongTermDebtRollforwardRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7575ee23-3cd9-4482-98a5-1bd802a6ca61" xlink:to="loc_oxy_LongTermDebtRollforwardRollForward_b82be371-deb2-4e05-a53d-50481cdafce4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_152f2411-faba-4590-937c-bc6f11121a6d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_LongTermDebtRollforwardRollForward_b82be371-deb2-4e05-a53d-50481cdafce4" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_152f2411-faba-4590-937c-bc6f11121a6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_52c70ed0-a215-44f2-ae73-97ad8dd6f43c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_LongTermDebtRollforwardRollForward_b82be371-deb2-4e05-a53d-50481cdafce4" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_52c70ed0-a215-44f2-ae73-97ad8dd6f43c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_1327aa43-5737-46c8-ae04-af7f9484e87c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_LongTermDebtRollforwardRollForward_b82be371-deb2-4e05-a53d-50481cdafce4" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_1327aa43-5737-46c8-ae04-af7f9484e87c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_7f4d4061-e808-4c7e-823d-e56d0b6e3adb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_LongTermDebtRollforwardRollForward_b82be371-deb2-4e05-a53d-50481cdafce4" xlink:to="loc_us-gaap_RepaymentsOfDebt_7f4d4061-e808-4c7e-823d-e56d0b6e3adb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_903fa180-ff10-43b0-a445-c112695b4822" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_972d291f-c752-4449-8368-877edbdf5b12" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_7575ee23-3cd9-4482-98a5-1bd802a6ca61" xlink:to="loc_us-gaap_DebtInstrumentTable_972d291f-c752-4449-8368-877edbdf5b12" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_4a407acf-cbdf-418e-91af-2d2c621eb121" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_972d291f-c752-4449-8368-877edbdf5b12" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_4a407acf-cbdf-418e-91af-2d2c621eb121" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4a407acf-cbdf-418e-91af-2d2c621eb121_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4a407acf-cbdf-418e-91af-2d2c621eb121" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4a407acf-cbdf-418e-91af-2d2c621eb121_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_302d33f8-dad8-4fbb-b114-57e736cdd0e7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4a407acf-cbdf-418e-91af-2d2c621eb121" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_302d33f8-dad8-4fbb-b114-57e736cdd0e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_d6a32073-2a91-436f-8804-89ff948bea35" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_302d33f8-dad8-4fbb-b114-57e736cdd0e7" xlink:to="loc_us-gaap_SeniorNotesMember_d6a32073-2a91-436f-8804-89ff948bea35" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_186ac910-31fd-45cb-9a32-ca1e64eb8159" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_972d291f-c752-4449-8368-877edbdf5b12" xlink:to="loc_us-gaap_DebtInstrumentAxis_186ac910-31fd-45cb-9a32-ca1e64eb8159" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_186ac910-31fd-45cb-9a32-ca1e64eb8159_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_186ac910-31fd-45cb-9a32-ca1e64eb8159" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_186ac910-31fd-45cb-9a32-ca1e64eb8159_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_186ac910-31fd-45cb-9a32-ca1e64eb8159" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDue20258000Member_65d53604-1269-4eb2-bec3-61cbf23278c9" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDue20258000Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDue20258000Member_65d53604-1269-4eb2-bec3-61cbf23278c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDue20278500Member_12a3084f-5039-41f4-9065-4965db2d02f9" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDue20278500Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDue20278500Member_12a3084f-5039-41f4-9065-4965db2d02f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDue20308875Member_51c40039-e81f-48ab-be6c-30cb0e8df9cf" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDue20308875Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDue20308875Member_51c40039-e81f-48ab-be6c-30cb0e8df9cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDueFebruary202141Member_b3f1af0c-7b2b-48fc-a2c4-b2df56fef0a6" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDueFebruary202141Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDueFebruary202141Member_b3f1af0c-7b2b-48fc-a2c4-b2df56fef0a6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_VariableRateBondsDue2021Member_6dc0e8f9-058e-41fa-82cc-8a97011ed7ae" xlink:href="oxy-20200930.xsd#oxy_VariableRateBondsDue2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_VariableRateBondsDue2021Member_6dc0e8f9-058e-41fa-82cc-8a97011ed7ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDueMarch20214850Member_dfbe1d20-02ac-4b67-a074-9cc130898aef" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDueMarch20214850Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDueMarch20214850Member_dfbe1d20-02ac-4b67-a074-9cc130898aef" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDueAugust20212600Member_2584032a-0f4b-4cb2-8be2-8d25f390386b" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDueAugust20212600Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDueAugust20212600Member_2584032a-0f4b-4cb2-8be2-8d25f390386b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDue20255875Member_26d2fb16-ece7-4199-bfdb-d12ca3e4b401" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDue20255875Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDue20255875Member_26d2fb16-ece7-4199-bfdb-d12ca3e4b401" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDue20286375Member_a8502dec-58cf-4517-8795-619f6a971ecb" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDue20286375Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDue20286375Member_a8502dec-58cf-4517-8795-619f6a971ecb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDue20306625Member_baa54c59-2708-443b-b803-33a8016523dc" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDue20306625Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDue20306625Member_baa54c59-2708-443b-b803-33a8016523dc" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_VariableRateBondsDue2022Member_d00d7519-f3f7-463d-b020-850d198d1b4e" xlink:href="oxy-20200930.xsd#oxy_VariableRateBondsDue2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_VariableRateBondsDue2022Member_d00d7519-f3f7-463d-b020-850d198d1b4e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDueApril20222600Member_c4a1de13-f722-4aba-95cd-f4dce157443d" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDueApril20222600Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDueApril20222600Member_c4a1de13-f722-4aba-95cd-f4dce157443d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDueAugust20222700Member_65e9ad6f-2fb0-4fba-86dc-d52f67b8ebff" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDueAugust20222700Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDueAugust20222700Member_65e9ad6f-2fb0-4fba-86dc-d52f67b8ebff" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeniorNotesDueFebruary20232700Member_91124910-143e-42eb-85ee-a635bdb976ba" xlink:href="oxy-20200930.xsd#oxy_SeniorNotesDueFebruary20232700Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_SeniorNotesDueFebruary20232700Member_91124910-143e-42eb-85ee-a635bdb976ba" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_NotePayableDue20386500Member_dd36a509-2d15-4c6e-89c1-2633fdc894d2" xlink:href="oxy-20200930.xsd#oxy_NotePayableDue20386500Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_NotePayableDue20386500Member_dd36a509-2d15-4c6e-89c1-2633fdc894d2" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_VariableRateTermLoanDue2021Member_9ddca756-1bb4-44b6-ba6a-9f05741bedf4" xlink:href="oxy-20200930.xsd#oxy_VariableRateTermLoanDue2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8c3acc40-809c-4f88-acfe-20671cf6f37f" xlink:to="loc_oxy_VariableRateTermLoanDue2021Member_9ddca756-1bb4-44b6-ba6a-9f05741bedf4" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DebtInstrumentPeriodAxis_df8317ff-d0ef-48ea-9d9c-20cca0e572a7" xlink:href="oxy-20200930.xsd#oxy_DebtInstrumentPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_972d291f-c752-4449-8368-877edbdf5b12" xlink:to="loc_oxy_DebtInstrumentPeriodAxis_df8317ff-d0ef-48ea-9d9c-20cca0e572a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DebtInstrumentPeriodDomain_df8317ff-d0ef-48ea-9d9c-20cca0e572a7_default" xlink:href="oxy-20200930.xsd#oxy_DebtInstrumentPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_oxy_DebtInstrumentPeriodAxis_df8317ff-d0ef-48ea-9d9c-20cca0e572a7" xlink:to="loc_oxy_DebtInstrumentPeriodDomain_df8317ff-d0ef-48ea-9d9c-20cca0e572a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:href="oxy-20200930.xsd#oxy_DebtInstrumentPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_oxy_DebtInstrumentPeriodAxis_df8317ff-d0ef-48ea-9d9c-20cca0e572a7" xlink:to="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_IssuanceOfJuly2020NotesMember_8751ebaa-24ef-44bd-a41a-0e13b6ec155d" xlink:href="oxy-20200930.xsd#oxy_IssuanceOfJuly2020NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:to="loc_oxy_IssuanceOfJuly2020NotesMember_8751ebaa-24ef-44bd-a41a-0e13b6ec155d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_JulyTenderAndPurchaseMember_b4ec2386-063e-4803-b749-00744e23092b" xlink:href="oxy-20200930.xsd#oxy_JulyTenderAndPurchaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:to="loc_oxy_JulyTenderAndPurchaseMember_b4ec2386-063e-4803-b749-00744e23092b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_IssuanceOfAugust2020NotesMember_24536a23-9e7c-4f49-a2a5-7a384506bdf5" xlink:href="oxy-20200930.xsd#oxy_IssuanceOfAugust2020NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:to="loc_oxy_IssuanceOfAugust2020NotesMember_24536a23-9e7c-4f49-a2a5-7a384506bdf5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AugustAndSeptemberTenderAndPurchaseMember_5dc3cae2-e67a-48dc-aba1-438880c4aa79" xlink:href="oxy-20200930.xsd#oxy_AugustAndSeptemberTenderAndPurchaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:to="loc_oxy_AugustAndSeptemberTenderAndPurchaseMember_5dc3cae2-e67a-48dc-aba1-438880c4aa79" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AugustExchangeMember_91273d29-e031-43b5-83da-07898844b793" xlink:href="oxy-20200930.xsd#oxy_AugustExchangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:to="loc_oxy_AugustExchangeMember_91273d29-e031-43b5-83da-07898844b793" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_SeptemberRepaymentMember_2b09dc09-ee52-4adc-9dc3-22e5651f216d" xlink:href="oxy-20200930.xsd#oxy_SeptemberRepaymentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oxy_DebtInstrumentPeriodDomain_e806992b-b4ff-457b-8815-7552734d9dea" xlink:to="loc_oxy_SeptemberRepaymentMember_2b09dc09-ee52-4adc-9dc3-22e5651f216d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d16e6ba2-53db-49de-92c5-5f6c1031aaf0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_972d291f-c752-4449-8368-877edbdf5b12" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d16e6ba2-53db-49de-92c5-5f6c1031aaf0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_d16e6ba2-53db-49de-92c5-5f6c1031aaf0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d16e6ba2-53db-49de-92c5-5f6c1031aaf0" xlink:to="loc_us-gaap_RelatedPartyDomain_d16e6ba2-53db-49de-92c5-5f6c1031aaf0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_d82a8ee2-d46e-4d3f-b442-46e159f5ba14" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_d16e6ba2-53db-49de-92c5-5f6c1031aaf0" xlink:to="loc_us-gaap_RelatedPartyDomain_d82a8ee2-d46e-4d3f-b442-46e159f5ba14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_4fae028c-7326-4455-a6a1-78fd83d8e158" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_d82a8ee2-d46e-4d3f-b442-46e159f5ba14" xlink:to="loc_srt_AffiliatedEntityMember_4fae028c-7326-4455-a6a1-78fd83d8e158" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/LeaseCommitments" xlink:type="simple" xlink:href="oxy-20200930.xsd#LeaseCommitments"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LeaseCommitments" xlink:type="extended" id="i9a7a60f576c146b98f8e207deb51f020_LeaseCommitments"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LeaseCommitmentsTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#LeaseCommitmentsTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LeaseCommitmentsTables" xlink:type="extended" id="i09bc6485d169452e86e80e9574aee357_LeaseCommitmentsTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LeaseCommitmentsNarrativeDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LeaseCommitmentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LeaseCommitmentsNarrativeDetails" xlink:type="extended" id="idcb0270ddf0946f6886e2619a14f2bbf_LeaseCommitmentsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_3bbdb20a-c072-46b9-ae10-2cea39be5cc6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_e29c7f06-77f5-4617-ba59-1b01e2c4553f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_3bbdb20a-c072-46b9-ae10-2cea39be5cc6" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_e29c7f06-77f5-4617-ba59-1b01e2c4553f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_76a856da-7f99-48a4-986c-97c1f2a93c04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_3bbdb20a-c072-46b9-ae10-2cea39be5cc6" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_76a856da-7f99-48a4-986c-97c1f2a93c04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_2840b9d5-e5ae-4c0c-91d5-2e8deaf3d374" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_3bbdb20a-c072-46b9-ae10-2cea39be5cc6" xlink:to="loc_us-gaap_FinanceLeaseLiability_2840b9d5-e5ae-4c0c-91d5-2e8deaf3d374" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_f7803dde-99df-434d-b15a-44a43deb0d75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_3bbdb20a-c072-46b9-ae10-2cea39be5cc6" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_f7803dde-99df-434d-b15a-44a43deb0d75" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e4ffbc41-2c45-4ae2-bd24-9ad80e967833" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_f7803dde-99df-434d-b15a-44a43deb0d75" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e4ffbc41-2c45-4ae2-bd24-9ad80e967833" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e4ffbc41-2c45-4ae2-bd24-9ad80e967833_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e4ffbc41-2c45-4ae2-bd24-9ad80e967833" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e4ffbc41-2c45-4ae2-bd24-9ad80e967833_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e4ffbc41-2c45-4ae2-bd24-9ad80e967833" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OffshoreAndOnshoreDrillingRigsMember_87c8b088-905b-4334-a693-9fdfbe2ca959" xlink:href="oxy-20200930.xsd#oxy_OffshoreAndOnshoreDrillingRigsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_OffshoreAndOnshoreDrillingRigsMember_87c8b088-905b-4334-a693-9fdfbe2ca959" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_CompressorsMember_632a3d5e-28e4-4432-8026-172c4ddf4711" xlink:href="oxy-20200930.xsd#oxy_CompressorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_CompressorsMember_632a3d5e-28e4-4432-8026-172c4ddf4711" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_StorageFacilitiesMember_ac303e5d-6d88-4650-ada5-843ec3c63b2e" xlink:href="oxy-20200930.xsd#oxy_StorageFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_StorageFacilitiesMember_ac303e5d-6d88-4650-ada5-843ec3c63b2e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OfficeSpaceMember_3fa31724-b8d9-462f-99ef-99ebc481159a" xlink:href="oxy-20200930.xsd#oxy_OfficeSpaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_OfficeSpaceMember_3fa31724-b8d9-462f-99ef-99ebc481159a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OtherFieldEquipmentMember_84d6849a-cbe4-467b-bf35-4bfe15a9f0da" xlink:href="oxy-20200930.xsd#oxy_OtherFieldEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_OtherFieldEquipmentMember_84d6849a-cbe4-467b-bf35-4bfe15a9f0da" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_OilAndGasExplorationAndDevelopmentEquipmentMember_dce81077-ce4f-4199-b325-a7ff2ae56c47" xlink:href="oxy-20200930.xsd#oxy_OilAndGasExplorationAndDevelopmentEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_OilAndGasExplorationAndDevelopmentEquipmentMember_dce81077-ce4f-4199-b325-a7ff2ae56c47" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PipelinesRailCarsStorageFacilitiesEasementsAndRealEstateMember_6970cf25-fd95-444b-abb1-5c5ba8aa26e2" xlink:href="oxy-20200930.xsd#oxy_PipelinesRailCarsStorageFacilitiesEasementsAndRealEstateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_PipelinesRailCarsStorageFacilitiesEasementsAndRealEstateMember_6970cf25-fd95-444b-abb1-5c5ba8aa26e2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_RealEstateLeasesMember_dfc3d4f5-b61d-4a81-a6e6-90cd25beaf93" xlink:href="oxy-20200930.xsd#oxy_RealEstateLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_9ae069d9-3b61-467f-8215-dee076dfd319" xlink:to="loc_oxy_RealEstateLeasesMember_dfc3d4f5-b61d-4a81-a6e6-90cd25beaf93" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_99b25415-ac1c-400d-aaf1-b1b114b9fc72" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_f7803dde-99df-434d-b15a-44a43deb0d75" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_99b25415-ac1c-400d-aaf1-b1b114b9fc72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_99b25415-ac1c-400d-aaf1-b1b114b9fc72_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_99b25415-ac1c-400d-aaf1-b1b114b9fc72" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_99b25415-ac1c-400d-aaf1-b1b114b9fc72_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f9b36442-53c5-478e-8cf9-715103cf95e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_99b25415-ac1c-400d-aaf1-b1b114b9fc72" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f9b36442-53c5-478e-8cf9-715103cf95e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_fef0e3df-261a-4898-ac1d-ed423fc9b8dc" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f9b36442-53c5-478e-8cf9-715103cf95e2" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_fef0e3df-261a-4898-ac1d-ed423fc9b8dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_0c711537-40d3-41f9-9623-f298a287ecb1" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_f7803dde-99df-434d-b15a-44a43deb0d75" xlink:to="loc_srt_RangeAxis_0c711537-40d3-41f9-9623-f298a287ecb1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0c711537-40d3-41f9-9623-f298a287ecb1_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_0c711537-40d3-41f9-9623-f298a287ecb1" xlink:to="loc_srt_RangeMember_0c711537-40d3-41f9-9623-f298a287ecb1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_844ab6f9-f13b-4b41-8113-77c4c779295d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_0c711537-40d3-41f9-9623-f298a287ecb1" xlink:to="loc_srt_RangeMember_844ab6f9-f13b-4b41-8113-77c4c779295d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_d074e437-e465-4d67-a470-e36ad7435de6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_844ab6f9-f13b-4b41-8113-77c4c779295d" xlink:to="loc_srt_MinimumMember_d074e437-e465-4d67-a470-e36ad7435de6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e3a51298-3360-407e-9396-ede50e876fb8" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_844ab6f9-f13b-4b41-8113-77c4c779295d" xlink:to="loc_srt_MaximumMember_e3a51298-3360-407e-9396-ede50e876fb8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/LeaseCommitmentsLeaseAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LeaseCommitmentsLeaseAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LeaseCommitmentsLeaseAssetsandLiabilitiesDetails" xlink:type="extended" id="ie541f47a0da141349f4a19512dc589e4_LeaseCommitmentsLeaseAssetsandLiabilitiesDetails"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LeaseCommitmentsScheduleofOperatingandFinanceLeaseMaturitiesDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LeaseCommitmentsScheduleofOperatingandFinanceLeaseMaturitiesDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LeaseCommitmentsScheduleofOperatingandFinanceLeaseMaturitiesDetails" xlink:type="extended" id="i22a7351bda0546d299555c406a0327b2_LeaseCommitmentsScheduleofOperatingandFinanceLeaseMaturitiesDetails"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LeaseCommitmentsOtherInformationDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LeaseCommitmentsOtherInformationDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LeaseCommitmentsOtherInformationDetails" xlink:type="extended" id="i03389aeb4f2c452f830e7443f6adb402_LeaseCommitmentsOtherInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_6fae847d-1012-4f0a-be9e-f35a52832882" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_OperatingLeaseCost_6fae847d-1012-4f0a-be9e-f35a52832882" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_61815a11-19bd-4dc0-847c-e9d7be522369" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization_61815a11-19bd-4dc0-847c-e9d7be522369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense_1c0869c5-78d2-4f00-9ad6-16eb729f38eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_FinanceLeaseInterestExpense_1c0869c5-78d2-4f00-9ad6-16eb729f38eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCost_bdf6514b-e6fc-4dcb-a340-78cdaf888954" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_LeaseCost_bdf6514b-e6fc-4dcb-a340-78cdaf888954" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCost_12c005ff-6a45-4f1e-aa1d-0e66aaa8bbaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShortTermLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_ShortTermLeaseCost_12c005ff-6a45-4f1e-aa1d-0e66aaa8bbaf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_2fb60ed2-9acb-4a1b-9fc5-7d25a2c2429b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_VariableLeaseCost_2fb60ed2-9acb-4a1b-9fc5-7d25a2c2429b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_1ebfee65-f8a4-474e-9b6e-e250143f15be" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_OperatingLeasePayments_1ebfee65-f8a4-474e-9b6e-e250143f15be" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePaymentsUse_3cd8ab58-7232-4c00-9fab-50a67d9a2b8e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasePaymentsUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_OperatingLeasePaymentsUse_3cd8ab58-7232-4c00-9fab-50a67d9a2b8e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_2970562a-d2a8-4da2-bbfd-1759f4357d6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_2970562a-d2a8-4da2-bbfd-1759f4357d6e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_4c43816f-1c42-4f82-9a9c-0ac36189eb52" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_1b3fc596-d431-4c17-9dce-f6ca10d14fd0" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_4c43816f-1c42-4f82-9a9c-0ac36189eb52" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_1740acca-9b4c-40ac-a119-f79abf5780bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_4c43816f-1c42-4f82-9a9c-0ac36189eb52" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_1740acca-9b4c-40ac-a119-f79abf5780bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1740acca-9b4c-40ac-a119-f79abf5780bd_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_1740acca-9b4c-40ac-a119-f79abf5780bd" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1740acca-9b4c-40ac-a119-f79abf5780bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_21a90b8d-7b5a-4c75-8526-49c3cea304af" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_1740acca-9b4c-40ac-a119-f79abf5780bd" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_21a90b8d-7b5a-4c75-8526-49c3cea304af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentMember_6fe2a09e-8e29-46fd-882c-e1f6a94cb7aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_21a90b8d-7b5a-4c75-8526-49c3cea304af" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentMember_6fe2a09e-8e29-46fd-882c-e1f6a94cb7aa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_898249e3-487c-4bce-9683-bcfa58dfe308" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_21a90b8d-7b5a-4c75-8526-49c3cea304af" xlink:to="loc_us-gaap_CostOfSalesMember_898249e3-487c-4bce-9683-bcfa58dfe308" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_3622c97d-5210-4e07-973d-d2e5ee6e9e6b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_21a90b8d-7b5a-4c75-8526-49c3cea304af" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_3622c97d-5210-4e07-973d-d2e5ee6e9e6b" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/LawsuitsClaimsCommitmentsandContingencies" xlink:type="simple" xlink:href="oxy-20200930.xsd#LawsuitsClaimsCommitmentsandContingencies"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LawsuitsClaimsCommitmentsandContingencies" xlink:type="extended" id="i3235caea76904133a758b5ea9d1fbaae_LawsuitsClaimsCommitmentsandContingencies"/>
  <link:roleRef roleURI="http://www.oxy.com/role/LawsuitsClaimsCommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#LawsuitsClaimsCommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/LawsuitsClaimsCommitmentsandContingenciesDetails" xlink:type="extended" id="i6e0cc6e125724c16900a52470c3b4a74_LawsuitsClaimsCommitmentsandContingenciesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermPurchaseCommitmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLegalSettlements_f6440c35-a5c5-4bc9-8d81-a6e7f5a97a87" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_us-gaap_ProceedsFromLegalSettlements_f6440c35-a5c5-4bc9-8d81-a6e7f5a97a87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PercentageOfRecoveryAmountAwardedInSettlementAmount_1dfe823e-e49a-48c7-8dd1-7edcf9744998" xlink:href="oxy-20200930.xsd#oxy_PercentageOfRecoveryAmountAwardedInSettlementAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_oxy_PercentageOfRecoveryAmountAwardedInSettlementAmount_1dfe823e-e49a-48c7-8dd1-7edcf9744998" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PercentageOfLitigationSettlementClaimed_f3a45c71-f0f8-4abd-92b0-5e5a61d43d34" xlink:href="oxy-20200930.xsd#oxy_PercentageOfLitigationSettlementClaimed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_oxy_PercentageOfLitigationSettlementClaimed_f3a45c71-f0f8-4abd-92b0-5e5a61d43d34" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PercentageOfOwnEconomicInterest_4ac5b6d7-e345-43ad-ae0b-4a4e6306f7ad" xlink:href="oxy-20200930.xsd#oxy_PercentageOfOwnEconomicInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_oxy_PercentageOfOwnEconomicInterest_4ac5b6d7-e345-43ad-ae0b-4a4e6306f7ad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIncomeTaxRefunds_a0c65dd0-6d50-4a4f-a9a2-6142e72c010b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIncomeTaxRefunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_us-gaap_ProceedsFromIncomeTaxRefunds_a0c65dd0-6d50-4a4f-a9a2-6142e72c010b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_4b35019d-7940-4b33-bc29-0a159b33f506" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_4b35019d-7940-4b33-bc29-0a159b33f506" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AlternativeMinimumTaxCreditAndNetOperatingLossCarrybackAnticipatedCashRefund_6272a6e0-7753-4d17-8e49-d50cf2c5b4da" xlink:href="oxy-20200930.xsd#oxy_AlternativeMinimumTaxCreditAndNetOperatingLossCarrybackAnticipatedCashRefund"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_oxy_AlternativeMinimumTaxCreditAndNetOperatingLossCarrybackAnticipatedCashRefund_6272a6e0-7753-4d17-8e49-d50cf2c5b4da" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentTable_d421b51a-f77a-4bac-bb96-5211eae2db39" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermPurchaseCommitmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_103e7acc-67ea-4899-851b-604e3ed1ec3d" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentTable_d421b51a-f77a-4bac-bb96-5211eae2db39" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_9e24a797-bd56-413d-8b26-9d1089e541f9" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_d421b51a-f77a-4bac-bb96-5211eae2db39" xlink:to="loc_srt_LitigationCaseAxis_9e24a797-bd56-413d-8b26-9d1089e541f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_9e24a797-bd56-413d-8b26-9d1089e541f9_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_9e24a797-bd56-413d-8b26-9d1089e541f9" xlink:to="loc_srt_LitigationCaseTypeDomain_9e24a797-bd56-413d-8b26-9d1089e541f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_9af7d2dd-83e8-4bd9-aa84-d1f68166ff4a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_9e24a797-bd56-413d-8b26-9d1089e541f9" xlink:to="loc_srt_LitigationCaseTypeDomain_9af7d2dd-83e8-4bd9-aa84-d1f68166ff4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ArbitrationDemandFiledByAndesPetroleumEcuadorLtdMember_67eb080a-3000-4399-814d-6f2f981d5295" xlink:href="oxy-20200930.xsd#oxy_ArbitrationDemandFiledByAndesPetroleumEcuadorLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_9af7d2dd-83e8-4bd9-aa84-d1f68166ff4a" xlink:to="loc_oxy_ArbitrationDemandFiledByAndesPetroleumEcuadorLtdMember_67eb080a-3000-4399-814d-6f2f981d5295" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_TronoxSettlementMember_d4ac330e-ff26-4bfd-bee5-ab9e522a89c1" xlink:href="oxy-20200930.xsd#oxy_TronoxSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_9af7d2dd-83e8-4bd9-aa84-d1f68166ff4a" xlink:to="loc_oxy_TronoxSettlementMember_d4ac330e-ff26-4bfd-bee5-ab9e522a89c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_95fceb57-a498-40c4-9669-f4da5c01d6d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_d421b51a-f77a-4bac-bb96-5211eae2db39" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_95fceb57-a498-40c4-9669-f4da5c01d6d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_95fceb57-a498-40c4-9669-f4da5c01d6d4_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_95fceb57-a498-40c4-9669-f4da5c01d6d4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_95fceb57-a498-40c4-9669-f4da5c01d6d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d58dc76c-2345-41dd-9071-57032751400c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_95fceb57-a498-40c4-9669-f4da5c01d6d4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d58dc76c-2345-41dd-9071-57032751400c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_eabfb1cc-5bfa-4b52-9fa1-121c5a6cd96b" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d58dc76c-2345-41dd-9071-57032751400c" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_eabfb1cc-5bfa-4b52-9fa1-121c5a6cd96b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/EnvironmentalLiabilitiesandExpenditures" xlink:type="simple" xlink:href="oxy-20200930.xsd#EnvironmentalLiabilitiesandExpenditures"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EnvironmentalLiabilitiesandExpenditures" xlink:type="extended" id="i9de402526fd8452eb0b21a706bc56d87_EnvironmentalLiabilitiesandExpenditures"/>
  <link:roleRef roleURI="http://www.oxy.com/role/EnvironmentalLiabilitiesandExpendituresTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#EnvironmentalLiabilitiesandExpendituresTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EnvironmentalLiabilitiesandExpendituresTables" xlink:type="extended" id="i12ebfd6c1f204ba8904226108dd25015_EnvironmentalLiabilitiesandExpendituresTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/EnvironmentalLiabilitiesandExpendituresDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#EnvironmentalLiabilitiesandExpendituresDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EnvironmentalLiabilitiesandExpendituresDetails" xlink:type="extended" id="i0d7e676adc3e47b3bbbc62abb8685740_EnvironmentalLiabilitiesandExpendituresDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SiteContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EnvironmentalRemediationSitesNumber_54d7ee2b-24ef-4910-869f-1fb3f2490ecd" xlink:href="oxy-20200930.xsd#oxy_EnvironmentalRemediationSitesNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_EnvironmentalRemediationSitesNumber_54d7ee2b-24ef-4910-869f-1fb3f2490ecd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesCurrent_0cd20470-4994-4ecc-a642-4348e3267c6c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedEnvironmentalLossContingenciesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesCurrent_0cd20470-4994-4ecc-a642-4348e3267c6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_d42cc391-a2d7-42c0-937b-a1e637ef7322" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_d42cc391-a2d7-42c0-937b-a1e637ef7322" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EnvironmentalReservesExceedingTenMillionThresholdValueSiteCategory_98d8d2b6-1878-4d20-b69a-1cf67cb1a422" xlink:href="oxy-20200930.xsd#oxy_EnvironmentalReservesExceedingTenMillionThresholdValueSiteCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_EnvironmentalReservesExceedingTenMillionThresholdValueSiteCategory_98d8d2b6-1878-4d20-b69a-1cf67cb1a422" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EnvironmentalReservesExceedingTenMillionSiteCategoryNumberOfSites_62661a4a-34c9-4e69-b733-20fde0991780" xlink:href="oxy-20200930.xsd#oxy_EnvironmentalReservesExceedingTenMillionSiteCategoryNumberOfSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_EnvironmentalReservesExceedingTenMillionSiteCategoryNumberOfSites_62661a4a-34c9-4e69-b733-20fde0991780" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EnvironmentalReservesRangeBetweenZeroToOneMillionSiteCategoryNumberOfSites_acc9306d-1c3d-4bbe-b898-be5c06d2ec12" xlink:href="oxy-20200930.xsd#oxy_EnvironmentalReservesRangeBetweenZeroToOneMillionSiteCategoryNumberOfSites"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_EnvironmentalReservesRangeBetweenZeroToOneMillionSiteCategoryNumberOfSites_acc9306d-1c3d-4bbe-b898-be5c06d2ec12" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EnvironmentalReservesRangeBetweenZeroToOneMillionThresholdValueSiteCategory_a240da13-815d-4f45-ae95-4cd06a66b52e" xlink:href="oxy-20200930.xsd#oxy_EnvironmentalReservesRangeBetweenZeroToOneMillionThresholdValueSiteCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_EnvironmentalReservesRangeBetweenZeroToOneMillionThresholdValueSiteCategory_a240da13-815d-4f45-ae95-4cd06a66b52e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PercentageOfExpectedFundsEnvironmentalReserves_c4fee4a3-34c0-486f-977a-ebb815ef02e5" xlink:href="oxy-20200930.xsd#oxy_PercentageOfExpectedFundsEnvironmentalReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_PercentageOfExpectedFundsEnvironmentalReserves_c4fee4a3-34c0-486f-977a-ebb815ef02e5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PeriodOfExpendingFirstHalfOfEnvironmentalReserves_9b213202-2cec-4121-a891-cb1e6ff44eec" xlink:href="oxy-20200930.xsd#oxy_PeriodOfExpendingFirstHalfOfEnvironmentalReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_PeriodOfExpendingFirstHalfOfEnvironmentalReserves_9b213202-2cec-4121-a891-cb1e6ff44eec" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PeriodOfExpendingRemainingEnvironmentalReserves_8b6e88db-8ef1-4a0b-b098-6aaba8ec049c" xlink:href="oxy-20200930.xsd#oxy_PeriodOfExpendingRemainingEnvironmentalReserves"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_PeriodOfExpendingRemainingEnvironmentalReserves_8b6e88db-8ef1-4a0b-b098-6aaba8ec049c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EnvironmentalRemediationPossibleAdditionalLossBeyondAccruals_e730563a-8fac-43cb-8cfb-6007e4e502f0" xlink:href="oxy-20200930.xsd#oxy_EnvironmentalRemediationPossibleAdditionalLossBeyondAccruals"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_EnvironmentalRemediationPossibleAdditionalLossBeyondAccruals_e730563a-8fac-43cb-8cfb-6007e4e502f0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_RiverStretchWhichRequireRemedialActions_2767abb8-6aa8-4b21-a23c-75243dda92e9" xlink:href="oxy-20200930.xsd#oxy_RiverStretchWhichRequireRemedialActions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_RiverStretchWhichRequireRemedialActions_2767abb8-6aa8-4b21-a23c-75243dda92e9" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_RiverStretchWhichMayRequireRemedialActions_cb43b118-9f40-40a8-861b-6e09cad97d15" xlink:href="oxy-20200930.xsd#oxy_RiverStretchWhichMayRequireRemedialActions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_RiverStretchWhichMayRequireRemedialActions_cb43b118-9f40-40a8-861b-6e09cad97d15" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_CleanUpPlanEstimatedCost_6a23af38-c415-4a40-aae3-d263613acf1d" xlink:href="oxy-20200930.xsd#oxy_CleanUpPlanEstimatedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_oxy_CleanUpPlanEstimatedCost_6a23af38-c415-4a40-aae3-d263613acf1d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SiteContingencyTable_6dc539a8-f040-44fa-af0f-83c1fe42247f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SiteContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SiteContingencyLineItems_65b7bf8f-62d8-4a9a-bf0e-6bb3f714c065" xlink:to="loc_us-gaap_SiteContingencyTable_6dc539a8-f040-44fa-af0f-83c1fe42247f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_28cb2ccf-1726-4c2e-b8e7-6413feaf845d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SiteContingencyTable_6dc539a8-f040-44fa-af0f-83c1fe42247f" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_28cb2ccf-1726-4c2e-b8e7-6413feaf845d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_28cb2ccf-1726-4c2e-b8e7-6413feaf845d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_28cb2ccf-1726-4c2e-b8e7-6413feaf845d" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_28cb2ccf-1726-4c2e-b8e7-6413feaf845d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_30beac33-fc2b-49f0-b779-b6ffe40756e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_28cb2ccf-1726-4c2e-b8e7-6413feaf845d" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_30beac33-fc2b-49f0-b779-b6ffe40756e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_b36ef465-b3f4-43ed-bba9-f8b59c352e02" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_30beac33-fc2b-49f0-b779-b6ffe40756e4" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_b36ef465-b3f4-43ed-bba9-f8b59c352e02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DeferredCreditsAndOtherLiabilitiesMember_34d56ddd-7b97-47f1-8b76-6eca078be70d" xlink:href="oxy-20200930.xsd#oxy_DeferredCreditsAndOtherLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_30beac33-fc2b-49f0-b779-b6ffe40756e4" xlink:to="loc_oxy_DeferredCreditsAndOtherLiabilitiesMember_34d56ddd-7b97-47f1-8b76-6eca078be70d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRemediationSiteAxis_37a39a39-d4d7-49c4-b5d8-8f3489667c31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EnvironmentalRemediationSiteAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SiteContingencyTable_6dc539a8-f040-44fa-af0f-83c1fe42247f" xlink:to="loc_us-gaap_EnvironmentalRemediationSiteAxis_37a39a39-d4d7-49c4-b5d8-8f3489667c31" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRemediationSiteDomain_37a39a39-d4d7-49c4-b5d8-8f3489667c31_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EnvironmentalRemediationSiteDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteAxis_37a39a39-d4d7-49c4-b5d8-8f3489667c31" xlink:to="loc_us-gaap_EnvironmentalRemediationSiteDomain_37a39a39-d4d7-49c4-b5d8-8f3489667c31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EnvironmentalRemediationSiteDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteAxis_37a39a39-d4d7-49c4-b5d8-8f3489667c31" xlink:to="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_NPLSitesMember_d26d1e77-b14f-4dc3-856f-9297366de269" xlink:href="oxy-20200930.xsd#oxy_NPLSitesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:to="loc_oxy_NPLSitesMember_d26d1e77-b14f-4dc3-856f-9297366de269" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ThirdPartySitesMember_2cd0cae6-c796-4406-afcb-bd651caacbbf" xlink:href="oxy-20200930.xsd#oxy_ThirdPartySitesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:to="loc_oxy_ThirdPartySitesMember_2cd0cae6-c796-4406-afcb-bd651caacbbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_EntityOperatedSitesMember_b0061c3b-d6cf-446a-8e19-fa5923ed5604" xlink:href="oxy-20200930.xsd#oxy_EntityOperatedSitesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:to="loc_oxy_EntityOperatedSitesMember_b0061c3b-d6cf-446a-8e19-fa5923ed5604" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClosedOrNonOperatedEntitySitesMember_5e0f5492-2373-419a-bc50-7bd9431b9290" xlink:href="oxy-20200930.xsd#oxy_ClosedOrNonOperatedEntitySitesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:to="loc_oxy_ClosedOrNonOperatedEntitySitesMember_5e0f5492-2373-419a-bc50-7bd9431b9290" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PassaicRiverMember_745d293d-7a07-46e0-be90-48b04bdf5c0a" xlink:href="oxy-20200930.xsd#oxy_PassaicRiverMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EnvironmentalRemediationSiteDomain_5a0eceab-4326-44b9-957d-65b06860a795" xlink:to="loc_oxy_PassaicRiverMember_745d293d-7a07-46e0-be90-48b04bdf5c0a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6d1bd284-da13-45f3-be65-2845f08f7124" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SiteContingencyTable_6dc539a8-f040-44fa-af0f-83c1fe42247f" xlink:to="loc_srt_RangeAxis_6d1bd284-da13-45f3-be65-2845f08f7124" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6d1bd284-da13-45f3-be65-2845f08f7124_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6d1bd284-da13-45f3-be65-2845f08f7124" xlink:to="loc_srt_RangeMember_6d1bd284-da13-45f3-be65-2845f08f7124_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f74f5c88-a821-4b55-a7c9-293d5b3ea764" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6d1bd284-da13-45f3-be65-2845f08f7124" xlink:to="loc_srt_RangeMember_f74f5c88-a821-4b55-a7c9-293d5b3ea764" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_56d8b399-85ef-49f1-acf7-54b5be116774" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f74f5c88-a821-4b55-a7c9-293d5b3ea764" xlink:to="loc_srt_MinimumMember_56d8b399-85ef-49f1-acf7-54b5be116774" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ba647ac2-88c4-4242-ad05-596001643757" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f74f5c88-a821-4b55-a7c9-293d5b3ea764" xlink:to="loc_srt_MaximumMember_ba647ac2-88c4-4242-ad05-596001643757" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/RetirementandPostretirementBenefitPlans" xlink:type="simple" xlink:href="oxy-20200930.xsd#RetirementandPostretirementBenefitPlans"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RetirementandPostretirementBenefitPlans" xlink:type="extended" id="i0aa3d1f3dfc547f082629306dbddf851_RetirementandPostretirementBenefitPlans"/>
  <link:roleRef roleURI="http://www.oxy.com/role/RetirementandPostretirementBenefitsPlansTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#RetirementandPostretirementBenefitsPlansTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RetirementandPostretirementBenefitsPlansTables" xlink:type="extended" id="i3a822ac1d05a46a99fb45972f24766df_RetirementandPostretirementBenefitsPlansTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/RetirementandPostretirementBenefitPlansComponentsofNetPeriodicBenefitCostsDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#RetirementandPostretirementBenefitPlansComponentsofNetPeriodicBenefitCostsDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/RetirementandPostretirementBenefitPlansComponentsofNetPeriodicBenefitCostsDetails" xlink:type="extended" id="iff2fe4f0fa214c79871ac01d9c928a7d_RetirementandPostretirementBenefitPlansComponentsofNetPeriodicBenefitCostsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2da80747-b508-470f-b0a3-698613b6c68b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_60561b5f-6fbe-45a1-8ca7-57063956f5f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2da80747-b508-470f-b0a3-698613b6c68b" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_60561b5f-6fbe-45a1-8ca7-57063956f5f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsCurtailmentsAndSpecialTerminationBenefits_1a8959b9-9fda-4fad-8691-5b6e7c12a39e" xlink:href="oxy-20200930.xsd#oxy_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsCurtailmentsAndSpecialTerminationBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_60561b5f-6fbe-45a1-8ca7-57063956f5f0" xlink:to="loc_oxy_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsCurtailmentsAndSpecialTerminationBenefits_1a8959b9-9fda-4fad-8691-5b6e7c12a39e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_fb5d15da-936a-43cb-850f-27ba1e8ae9c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_60561b5f-6fbe-45a1-8ca7-57063956f5f0" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_fb5d15da-936a-43cb-850f-27ba1e8ae9c4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_ed3ae60f-601c-4f48-a7d9-3105ad0ebedb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_60561b5f-6fbe-45a1-8ca7-57063956f5f0" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_ed3ae60f-601c-4f48-a7d9-3105ad0ebedb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_92bceab4-1658-490d-8c98-58d7c07a0f8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2da80747-b508-470f-b0a3-698613b6c68b" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_92bceab4-1658-490d-8c98-58d7c07a0f8d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_e5dcb058-6968-4335-8790-ce49c6db27c5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_92bceab4-1658-490d-8c98-58d7c07a0f8d" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_e5dcb058-6968-4335-8790-ce49c6db27c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e5dcb058-6968-4335-8790-ce49c6db27c5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e5dcb058-6968-4335-8790-ce49c6db27c5" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e5dcb058-6968-4335-8790-ce49c6db27c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_8ce929fd-1d06-4dbd-b8e9-8e6c55837312" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e5dcb058-6968-4335-8790-ce49c6db27c5" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_8ce929fd-1d06-4dbd-b8e9-8e6c55837312" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_e7a0151b-af63-43c4-bead-3d2e357698d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_8ce929fd-1d06-4dbd-b8e9-8e6c55837312" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_e7a0151b-af63-43c4-bead-3d2e357698d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_ca4a5c19-2edd-4322-a216-10d97ed7f128" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_8ce929fd-1d06-4dbd-b8e9-8e6c55837312" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_ca4a5c19-2edd-4322-a216-10d97ed7f128" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquity" xlink:type="simple" xlink:href="oxy-20200930.xsd#EarningsPerShareAndStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquity" xlink:type="extended" id="i3be6e670b6464f9696418f68eaa9a47b_EarningsPerShareAndStockholdersEquity"/>
  <link:roleRef roleURI="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquityTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#EarningsPerShareAndStockholdersEquityTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquityTables" xlink:type="extended" id="i5aab585a33284bd6a42a8b5cb3ac1d59_EarningsPerShareAndStockholdersEquityTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquityDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#EarningsPerShareAndStockholdersEquityDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquityDetails" xlink:type="extended" id="id8926d0ebd3d4233b5bfccf7131c7006_EarningsPerShareAndStockholdersEquityDetails"/>
  <link:roleRef roleURI="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquityNarrativeDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#EarningsPerShareAndStockholdersEquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/EarningsPerShareAndStockholdersEquityNarrativeDetails" xlink:type="extended" id="i4baf5b56275243da95a2b5702de698fe_EarningsPerShareAndStockholdersEquityNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_722accca-759d-484f-90c2-fe6742ee07a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_722accca-759d-484f-90c2-fe6742ee07a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockLiquidationPreference_746ead79-64a7-457b-8436-a37aa6a3f703" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockLiquidationPreference"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_PreferredStockLiquidationPreference_746ead79-64a7-457b-8436-a37aa6a3f703" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendRatePercentage_4f34fcc0-ca32-4ada-ab25-553326f03a1d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_PreferredStockDividendRatePercentage_4f34fcc0-ca32-4ada-ab25-553326f03a1d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PreferredStockDividendRateForUnpaidAmountsPercentage_368b9e34-5eb3-45c7-9444-acd868cd5c94" xlink:href="oxy-20200930.xsd#oxy_PreferredStockDividendRateForUnpaidAmountsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_oxy_PreferredStockDividendRateForUnpaidAmountsPercentage_368b9e34-5eb3-45c7-9444-acd868cd5c94" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_ebc81e13-fa1c-41ab-bb37-8ca3122537fb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_ebc81e13-fa1c-41ab-bb37-8ca3122537fb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PreferredStockDividendVolumeWeightedAveragePrice_94d9e117-6d21-4bc3-9070-a049002cf14d" xlink:href="oxy-20200930.xsd#oxy_PreferredStockDividendVolumeWeightedAveragePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_oxy_PreferredStockDividendVolumeWeightedAveragePrice_94d9e117-6d21-4bc3-9070-a049002cf14d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_PreferredStockDividendVolumeWeightedAveragePriceCalculationPeriod_565d1fd3-1902-49cd-bc01-36e21bb1357c" xlink:href="oxy-20200930.xsd#oxy_PreferredStockDividendVolumeWeightedAveragePriceCalculationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_oxy_PreferredStockDividendVolumeWeightedAveragePriceCalculationPeriod_565d1fd3-1902-49cd-bc01-36e21bb1357c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_952d4727-c224-4e65-b686-6b4cecece47a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_952d4727-c224-4e65-b686-6b4cecece47a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClassOfWarrantOrRightConversionRate_adc98ed3-697a-4621-b6ae-62eb61b97dc2" xlink:href="oxy-20200930.xsd#oxy_ClassOfWarrantOrRightConversionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_oxy_ClassOfWarrantOrRightConversionRate_adc98ed3-697a-4621-b6ae-62eb61b97dc2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClassOfWarrantOrRightIssued_0d6902f6-be8b-4860-bd06-8f7d0df5970c" xlink:href="oxy-20200930.xsd#oxy_ClassOfWarrantOrRightIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_oxy_ClassOfWarrantOrRightIssued_0d6902f6-be8b-4860-bd06-8f7d0df5970c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1ba06e88-9e66-4591-b09e-d0af4360c344" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1ba06e88-9e66-4591-b09e-d0af4360c344" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ClassOfWarrantOrRightFairValue_9f9bb09e-18ad-4238-a997-413bfe0a3640" xlink:href="oxy-20200930.xsd#oxy_ClassOfWarrantOrRightFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_oxy_ClassOfWarrantOrRightFairValue_9f9bb09e-18ad-4238-a997-413bfe0a3640" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_70514c93-1fe4-41e3-a4e5-96d104a67ef2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_d16e0730-980b-4ab9-af97-689976144a0f" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_70514c93-1fe4-41e3-a4e5-96d104a67ef2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_f3a7ebcf-9d31-4f63-b06c-240f02898df8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_70514c93-1fe4-41e3-a4e5-96d104a67ef2" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_f3a7ebcf-9d31-4f63-b06c-240f02898df8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f3a7ebcf-9d31-4f63-b06c-240f02898df8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f3a7ebcf-9d31-4f63-b06c-240f02898df8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f3a7ebcf-9d31-4f63-b06c-240f02898df8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ba19602a-c409-4e09-9a91-30c0a9667300" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f3a7ebcf-9d31-4f63-b06c-240f02898df8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ba19602a-c409-4e09-9a91-30c0a9667300" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_AnadarkoPetroleumCorporationMember_dc893184-ae52-4817-91ba-f698965d457a" xlink:href="oxy-20200930.xsd#oxy_AnadarkoPetroleumCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ba19602a-c409-4e09-9a91-30c0a9667300" xlink:to="loc_oxy_AnadarkoPetroleumCorporationMember_dc893184-ae52-4817-91ba-f698965d457a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_bf634f8b-b35d-416a-ad95-8ae6f62d1c85" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_70514c93-1fe4-41e3-a4e5-96d104a67ef2" xlink:to="loc_us-gaap_StatementClassOfStockAxis_bf634f8b-b35d-416a-ad95-8ae6f62d1c85" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_bf634f8b-b35d-416a-ad95-8ae6f62d1c85_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_bf634f8b-b35d-416a-ad95-8ae6f62d1c85" xlink:to="loc_us-gaap_ClassOfStockDomain_bf634f8b-b35d-416a-ad95-8ae6f62d1c85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0365df0e-9987-4a5f-a28d-74cae8c240d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_bf634f8b-b35d-416a-ad95-8ae6f62d1c85" xlink:to="loc_us-gaap_ClassOfStockDomain_0365df0e-9987-4a5f-a28d-74cae8c240d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_80b36662-60e2-4271-ab06-4f2541ad252b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0365df0e-9987-4a5f-a28d-74cae8c240d8" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_80b36662-60e2-4271-ab06-4f2541ad252b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_6758bb25-8d6d-429e-831a-0025b3a3e892" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0365df0e-9987-4a5f-a28d-74cae8c240d8" xlink:to="loc_us-gaap_CommonStockMember_6758bb25-8d6d-429e-831a-0025b3a3e892" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_7bcd6e6d-09a6-4635-9667-d2e63b33d9c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_70514c93-1fe4-41e3-a4e5-96d104a67ef2" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_7bcd6e6d-09a6-4635-9667-d2e63b33d9c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_7bcd6e6d-09a6-4635-9667-d2e63b33d9c6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_7bcd6e6d-09a6-4635-9667-d2e63b33d9c6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_7bcd6e6d-09a6-4635-9667-d2e63b33d9c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_f3eeb9e4-666c-4f1a-aecc-351eca434a80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_7bcd6e6d-09a6-4635-9667-d2e63b33d9c6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_f3eeb9e4-666c-4f1a-aecc-351eca434a80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_e653be2a-c5b8-4a53-b707-a5fb4b1ca5f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_f3eeb9e4-666c-4f1a-aecc-351eca434a80" xlink:to="loc_us-gaap_SubsequentEventMember_e653be2a-c5b8-4a53-b707-a5fb4b1ca5f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_20983176-5ab8-425a-b820-b021b4459660" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_70514c93-1fe4-41e3-a4e5-96d104a67ef2" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_20983176-5ab8-425a-b820-b021b4459660" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_20983176-5ab8-425a-b820-b021b4459660_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_20983176-5ab8-425a-b820-b021b4459660" xlink:to="loc_us-gaap_EquityComponentDomain_20983176-5ab8-425a-b820-b021b4459660_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3490ebc5-90c3-44ae-b300-0bb06aa57a29" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_20983176-5ab8-425a-b820-b021b4459660" xlink:to="loc_us-gaap_EquityComponentDomain_3490ebc5-90c3-44ae-b300-0bb06aa57a29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_22cd6b9f-2dda-4e0e-a6f4-f3731f6e35e7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3490ebc5-90c3-44ae-b300-0bb06aa57a29" xlink:to="loc_us-gaap_WarrantMember_22cd6b9f-2dda-4e0e-a6f4-f3731f6e35e7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.oxy.com/role/IndustrySegments" xlink:type="simple" xlink:href="oxy-20200930.xsd#IndustrySegments"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/IndustrySegments" xlink:type="extended" id="i9690e922f4f64e48b7d912b3a42e49e6_IndustrySegments"/>
  <link:roleRef roleURI="http://www.oxy.com/role/IndustrySegmentsTables" xlink:type="simple" xlink:href="oxy-20200930.xsd#IndustrySegmentsTables"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/IndustrySegmentsTables" xlink:type="extended" id="i95cb52aa11e6405db298cc1d2ef18c5c_IndustrySegmentsTables"/>
  <link:roleRef roleURI="http://www.oxy.com/role/IndustrySegmentsScheduleofIndustrySegmentsandEliminationsDetails" xlink:type="simple" xlink:href="oxy-20200930.xsd#IndustrySegmentsScheduleofIndustrySegmentsandEliminationsDetails"/>
  <link:definitionLink xlink:role="http://www.oxy.com/role/IndustrySegmentsScheduleofIndustrySegmentsandEliminationsDetails" xlink:type="extended" id="icd286be1d51b4766b859c48e5670d7ae_IndustrySegmentsScheduleofIndustrySegmentsandEliminationsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_8867acd4-4848-409e-a55d-dbdd8e668fc0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_NumberOfOperatingSegments_8867acd4-4848-409e-a55d-dbdd8e668fc0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_9e76fa3f-1f52-4166-9245-709ab08dd693" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_Revenues_9e76fa3f-1f52-4166-9245-709ab08dd693" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_27f07e45-82a2-4943-98f9-b79e6d878a51" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_27f07e45-82a2-4943-98f9-b79e6d878a51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_ba577852-9469-42f5-8e56-1732039bade0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_ba577852-9469-42f5-8e56-1732039bade0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_ba5b3b21-5456-41fa-9b4d-94517e33d397" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_ba5b3b21-5456-41fa-9b4d-94517e33d397" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfOtherAssets_de6b6220-36dd-4262-8615-9e536a4af56e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnSaleOfOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_GainLossOnSaleOfOtherAssets_de6b6220-36dd-4262-8615-9e536a4af56e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_cbdb2e15-bf24-40a3-881b-8ebdb844094a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_AssetImpairmentCharges_cbdb2e15-bf24-40a3-881b-8ebdb844094a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_3cf6323d-b3ba-474a-b5ec-481c8a5833ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_3cf6323d-b3ba-474a-b5ec-481c8a5833ed" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_f55039cb-324b-42d4-8c90-2c75c20f2bcc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment_f55039cb-324b-42d4-8c90-2c75c20f2bcc" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_a09e41bb-f781-425a-9403-324039535318" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_a09e41bb-f781-425a-9403-324039535318" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_780dfee0-7126-4fa9-964c-0b99328f98e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_780dfee0-7126-4fa9-964c-0b99328f98e2" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments_dd9d4b20-fd23-4c49-9fd2-fbec33c1e9d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments_dd9d4b20-fd23-4c49-9fd2-fbec33c1e9d8" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_f1623b2c-10dd-4d32-a288-0a731e6cd77a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_f1623b2c-10dd-4d32-a288-0a731e6cd77a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c862155b-4d7c-4e19-a29b-043e44a5dae7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_fcae6884-7b5b-4c86-82d3-07db25a5f9c9" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c862155b-4d7c-4e19-a29b-043e44a5dae7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_2313bc6f-7fd6-466b-bd11-0d24151db175" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c862155b-4d7c-4e19-a29b-043e44a5dae7" xlink:to="loc_srt_ConsolidationItemsAxis_2313bc6f-7fd6-466b-bd11-0d24151db175" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_2313bc6f-7fd6-466b-bd11-0d24151db175_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_2313bc6f-7fd6-466b-bd11-0d24151db175" xlink:to="loc_srt_ConsolidationItemsDomain_2313bc6f-7fd6-466b-bd11-0d24151db175_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_73963e26-20f9-462e-a99a-6a0c6bc5a957" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_2313bc6f-7fd6-466b-bd11-0d24151db175" xlink:to="loc_srt_ConsolidationItemsDomain_73963e26-20f9-462e-a99a-6a0c6bc5a957" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_1b3e31bf-9ecb-48c5-8e68-dffa83376b47" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_73963e26-20f9-462e-a99a-6a0c6bc5a957" xlink:to="loc_us-gaap_OperatingSegmentsMember_1b3e31bf-9ecb-48c5-8e68-dffa83376b47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_CorporateReconcilingItemsAndEliminationsMember_122dc8ae-9f05-4b3e-afe2-cd2672052868" xlink:href="oxy-20200930.xsd#oxy_CorporateReconcilingItemsAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_73963e26-20f9-462e-a99a-6a0c6bc5a957" xlink:to="loc_oxy_CorporateReconcilingItemsAndEliminationsMember_122dc8ae-9f05-4b3e-afe2-cd2672052868" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_36b9b65d-2386-450a-ad73-5ddf77135068" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c862155b-4d7c-4e19-a29b-043e44a5dae7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_36b9b65d-2386-450a-ad73-5ddf77135068" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_36b9b65d-2386-450a-ad73-5ddf77135068_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_36b9b65d-2386-450a-ad73-5ddf77135068" xlink:to="loc_us-gaap_SegmentDomain_36b9b65d-2386-450a-ad73-5ddf77135068_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_88f13016-8aed-4276-a8d9-483819274d16" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_36b9b65d-2386-450a-ad73-5ddf77135068" xlink:to="loc_us-gaap_SegmentDomain_88f13016-8aed-4276-a8d9-483819274d16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OilAndGasMember_0d8bf831-a19c-48b0-8ef5-dc6879821bd4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OilAndGasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_88f13016-8aed-4276-a8d9-483819274d16" xlink:to="loc_us-gaap_OilAndGasMember_0d8bf831-a19c-48b0-8ef5-dc6879821bd4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_ChemicalMember_ac9d90d7-5700-427b-8919-8d24685a703e" xlink:href="oxy-20200930.xsd#oxy_ChemicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_88f13016-8aed-4276-a8d9-483819274d16" xlink:to="loc_oxy_ChemicalMember_ac9d90d7-5700-427b-8919-8d24685a703e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oxy_MidstreamAndMarketingMember_9c370a51-a461-4eca-a083-d5fd63df33b3" xlink:href="oxy-20200930.xsd#oxy_MidstreamAndMarketingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_88f13016-8aed-4276-a8d9-483819274d16" xlink:to="loc_oxy_MidstreamAndMarketingMember_9c370a51-a461-4eca-a083-d5fd63df33b3" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
