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

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2023 Workiva-->
<!--r:90b8f952-27c4-403e-bd1f-e3e50c83a4ff,g:72cea70c-4b7b-4b98-ad85-f69b6efa936f-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:avtr="http://us.avtr.com/20230331" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types1="http://www.xbrl.org/dtr/type/2020-01-21" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://us.avtr.com/20230331">
  <xs:import namespace="http://fasb.org/srt/2023" schemaLocation="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2023" schemaLocation="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd"/>
  <xs:import namespace="http://www.w3.org/1999/xlink" schemaLocation="http://www.xbrl.org/2003/xlink-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2023" schemaLocation="https://xbrl.sec.gov/country/2023/country-2023.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/currency/2023" schemaLocation="https://xbrl.sec.gov/currency/2023/currency-2023.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2023" schemaLocation="https://xbrl.sec.gov/dei/2023/dei-2023.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/stpr/2023" schemaLocation="https://xbrl.sec.gov/stpr/2023/stpr-2023.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="avtr-20230331_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="avtr-20230331_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="avtr-20230331_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="avtr-20230331_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Documentandentityinformation" roleURI="http://us.avtr.com/role/Documentandentityinformation">
        <link:definition>0000001 - Document - Document and entity information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Unauditedcondensedconsolidatedbalancesheets" roleURI="http://us.avtr.com/role/Unauditedcondensedconsolidatedbalancesheets">
        <link:definition>0000002 - Statement - Unaudited condensed consolidated balance sheets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="UnauditedcondensedconsolidatedbalancesheetsParenthetical" roleURI="http://us.avtr.com/role/UnauditedcondensedconsolidatedbalancesheetsParenthetical">
        <link:definition>0000003 - Statement - Unaudited condensed consolidated balance sheets (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Unauditedcondensedconsolidatedstatementsofoperations" roleURI="http://us.avtr.com/role/Unauditedcondensedconsolidatedstatementsofoperations">
        <link:definition>0000004 - Statement - Unaudited condensed consolidated statements of operations</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Unauditedcondensedconsolidatedstatementsofcomprehensiveincomeorloss" roleURI="http://us.avtr.com/role/Unauditedcondensedconsolidatedstatementsofcomprehensiveincomeorloss">
        <link:definition>0000005 - Statement - Unaudited condensed consolidated statements of comprehensive income or loss</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Unauditedcondensedconsolidatedstatementsofstockholdersequityordeficitshares" roleURI="http://us.avtr.com/role/Unauditedcondensedconsolidatedstatementsofstockholdersequityordeficitshares">
        <link:definition>0000006 - Statement - Unaudited condensed consolidated statements of stockholders' equity or deficit - shares</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Unauditedcondensedconsolidatedstatementsofstockholdersequityordeficitamounts" roleURI="http://us.avtr.com/role/Unauditedcondensedconsolidatedstatementsofstockholdersequityordeficitamounts">
        <link:definition>0000007 - Statement - Unaudited condensed consolidated statements of stockholders' equity or deficit - amounts</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Unauditedcondensedconsolidatedstatementsofcashflows" roleURI="http://us.avtr.com/role/Unauditedcondensedconsolidatedstatementsofcashflows">
        <link:definition>0000008 - Statement - Unaudited condensed consolidated statements of cash flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Natureofoperationsandpresentationoffinancialstatements" roleURI="http://us.avtr.com/role/Natureofoperationsandpresentationoffinancialstatements">
        <link:definition>0000009 - Disclosure - Nature of operations and presentation of financial statements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Earningspershare" roleURI="http://us.avtr.com/role/Earningspershare">
        <link:definition>0000010 - Disclosure - Earnings per share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Segmentfinancialinformation" roleURI="http://us.avtr.com/role/Segmentfinancialinformation">
        <link:definition>0000011 - Disclosure - Segment financial information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Supplementaldisclosuresofcashflowinformation" roleURI="http://us.avtr.com/role/Supplementaldisclosuresofcashflowinformation">
        <link:definition>0000012 - Disclosure - Supplemental disclosures of cash flow information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Inventory" roleURI="http://us.avtr.com/role/Inventory">
        <link:definition>0000013 - Disclosure - Inventory</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Otherintangibleassets" roleURI="http://us.avtr.com/role/Otherintangibleassets">
        <link:definition>0000014 - Disclosure - Other intangible assets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Commitmentsandcontingencies" roleURI="http://us.avtr.com/role/Commitmentsandcontingencies">
        <link:definition>0000015 - Disclosure - Commitments and contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Debt" roleURI="http://us.avtr.com/role/Debt">
        <link:definition>0000016 - Disclosure - Debt</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Accumulatedothercomprehensiveincomeorloss" roleURI="http://us.avtr.com/role/Accumulatedothercomprehensiveincomeorloss">
        <link:definition>0000017 - Disclosure - Accumulated other comprehensive income or loss</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Stockbasedcompensation" roleURI="http://us.avtr.com/role/Stockbasedcompensation">
        <link:definition>0000018 - Disclosure - Stock-based compensation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Otherincomeorexpensenet" roleURI="http://us.avtr.com/role/Otherincomeorexpensenet">
        <link:definition>0000019 - Disclosure - Other income or expense, net</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Incometaxes" roleURI="http://us.avtr.com/role/Incometaxes">
        <link:definition>0000020 - Disclosure - Income taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Derivativeandhedgingactivities" roleURI="http://us.avtr.com/role/Derivativeandhedgingactivities">
        <link:definition>0000021 - Disclosure - Derivative and hedging activities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Financialinstrumentsandfairvaluemeasurements" roleURI="http://us.avtr.com/role/Financialinstrumentsandfairvaluemeasurements">
        <link:definition>0000022 - Disclosure - Financial instruments and fair value measurements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NatureofoperationsandpresentationoffinancialstatementsPolicies" roleURI="http://us.avtr.com/role/NatureofoperationsandpresentationoffinancialstatementsPolicies">
        <link:definition>0000023 - Disclosure - Nature of operations and presentation of financial statements (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EarningspershareTables" roleURI="http://us.avtr.com/role/EarningspershareTables">
        <link:definition>0000024 - Disclosure - Earnings per share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentfinancialinformationTables" roleURI="http://us.avtr.com/role/SegmentfinancialinformationTables">
        <link:definition>0000025 - Disclosure - Segment financial information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SupplementaldisclosuresofcashflowinformationTables" roleURI="http://us.avtr.com/role/SupplementaldisclosuresofcashflowinformationTables">
        <link:definition>0000026 - Disclosure - Supplemental disclosures of cash flow information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoryTables" roleURI="http://us.avtr.com/role/InventoryTables">
        <link:definition>0000027 - Disclosure - Inventory (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherintangibleassetsTables" roleURI="http://us.avtr.com/role/OtherintangibleassetsTables">
        <link:definition>0000028 - Disclosure - Other intangible assets (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtTables" roleURI="http://us.avtr.com/role/DebtTables">
        <link:definition>0000029 - Disclosure - Debt (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedothercomprehensiveincomeorlossTables" roleURI="http://us.avtr.com/role/AccumulatedothercomprehensiveincomeorlossTables">
        <link:definition>0000030 - Disclosure - Accumulated other comprehensive income or loss (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedcompensationTables" roleURI="http://us.avtr.com/role/StockbasedcompensationTables">
        <link:definition>0000031 - Disclosure - Stock-based compensation (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherincomeorexpensenetTables" roleURI="http://us.avtr.com/role/OtherincomeorexpensenetTables">
        <link:definition>0000032 - Disclosure - Other income or expense, net (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncometaxesTables" roleURI="http://us.avtr.com/role/IncometaxesTables">
        <link:definition>0000033 - Disclosure - Income taxes (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesTables" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesTables">
        <link:definition>0000034 - Disclosure - Derivative and hedging activities (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FinancialinstrumentsandfairvaluemeasurementsTables" roleURI="http://us.avtr.com/role/FinancialinstrumentsandfairvaluemeasurementsTables">
        <link:definition>0000035 - Disclosure - Financial instruments and fair value measurements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NatureofoperationsandpresentationoffinancialstatementsDetails" roleURI="http://us.avtr.com/role/NatureofoperationsandpresentationoffinancialstatementsDetails">
        <link:definition>0000036 - Disclosure - Nature of operations and presentation of financial statements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EarningspersharereconciliationDetails" roleURI="http://us.avtr.com/role/EarningspersharereconciliationDetails">
        <link:definition>0000037 - Disclosure - Earnings per share - reconciliation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentfinancialinformationNarrativeDetails" roleURI="http://us.avtr.com/role/SegmentfinancialinformationNarrativeDetails">
        <link:definition>0000038 - Disclosure - Segment financial information - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentfinancialinformationreportablesegmentsDetails" roleURI="http://us.avtr.com/role/SegmentfinancialinformationreportablesegmentsDetails">
        <link:definition>0000039 - Disclosure - Segment financial information - reportable segments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentfinancialinformationreconciliationofsegmentprofitabilitymeasureDetails" roleURI="http://us.avtr.com/role/SegmentfinancialinformationreconciliationofsegmentprofitabilitymeasureDetails">
        <link:definition>0000040 - Disclosure - Segment financial information - reconciliation of segment profitability measure (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentfinancialinformationproductlinesDetails" roleURI="http://us.avtr.com/role/SegmentfinancialinformationproductlinesDetails">
        <link:definition>0000041 - Disclosure - Segment financial information - product lines (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SupplementaldisclosuresofcashflowinformationDetails" roleURI="http://us.avtr.com/role/SupplementaldisclosuresofcashflowinformationDetails">
        <link:definition>0000042 - Disclosure - Supplemental disclosures of cash flow information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoryDetails" roleURI="http://us.avtr.com/role/InventoryDetails">
        <link:definition>0000043 - Disclosure - Inventory (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherintangibleassetsDetails" roleURI="http://us.avtr.com/role/OtherintangibleassetsDetails">
        <link:definition>0000044 - Disclosure - Other intangible assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentsandcontingenciesDetails" roleURI="http://us.avtr.com/role/CommitmentsandcontingenciesDetails">
        <link:definition>0000045 - Disclosure - Commitments and contingencies (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtDetails" roleURI="http://us.avtr.com/role/DebtDetails">
        <link:definition>0000046 - Disclosure - Debt (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtDetails_1" roleURI="http://us.avtr.com/role/DebtDetails_1">
        <link:definition>0000046 - Disclosure - Debt (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtotherinformationDetails" roleURI="http://us.avtr.com/role/DebtotherinformationDetails">
        <link:definition>0000047 - Disclosure - Debt - other information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedothercomprehensiveincomeorlossDetails" roleURI="http://us.avtr.com/role/AccumulatedothercomprehensiveincomeorlossDetails">
        <link:definition>0000048 - Disclosure - Accumulated other comprehensive income or loss (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedcompensationexpenseDetails" roleURI="http://us.avtr.com/role/StockbasedcompensationexpenseDetails">
        <link:definition>0000049 - Disclosure - Stock-based compensation - expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedcompensationstockoptionrollforwardinformationDetails" roleURI="http://us.avtr.com/role/StockbasedcompensationstockoptionrollforwardinformationDetails">
        <link:definition>0000050 - Disclosure - Stock-based compensation - stock option rollforward information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedcompensationnonoptionawardrollforwardDetails" roleURI="http://us.avtr.com/role/StockbasedcompensationnonoptionawardrollforwardDetails">
        <link:definition>0000051 - Disclosure - Stock-based compensation - non-option award rollforward (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockbasedcompensationotherinformationDetails" roleURI="http://us.avtr.com/role/StockbasedcompensationotherinformationDetails">
        <link:definition>0000052 - Disclosure - Stock-based compensation - other information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherincomeorexpensenetDetails" roleURI="http://us.avtr.com/role/OtherincomeorexpensenetDetails">
        <link:definition>0000053 - Disclosure - Other income or expense, net (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncometaxesDetails" roleURI="http://us.avtr.com/role/IncometaxesDetails">
        <link:definition>0000054 - Disclosure - Income taxes (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesOutstandingInterestRateDerivativesDetails" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesOutstandingInterestRateDerivativesDetails">
        <link:definition>0000055 - Disclosure - Derivative and hedging activities - Outstanding Interest Rate Derivatives (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesEffectonAOCIDetails" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesEffectonAOCIDetails">
        <link:definition>0000056 - Disclosure - Derivative and hedging activities - Effect on AOCI (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesEffectonIncomeStatementDetails" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesEffectonIncomeStatementDetails">
        <link:definition>0000057 - Disclosure - Derivative and hedging activities - Effect on Income Statement (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesDerivativeInstrumentsClassificationonBalanceSheetDetails" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesDerivativeInstrumentsClassificationonBalanceSheetDetails">
        <link:definition>0000058 - Disclosure - Derivative and hedging activities - Derivative Instruments Classification on Balance Sheet (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesNarrativeDetails" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesNarrativeDetails">
        <link:definition>0000059 - Disclosure - Derivative and hedging activities - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativeandhedgingactivitiesGainLossonNetInvestmentHedgesDetails" roleURI="http://us.avtr.com/role/DerivativeandhedgingactivitiesGainLossonNetInvestmentHedgesDetails">
        <link:definition>0000060 - Disclosure - Derivative and hedging activities - Gain (Loss) on Net Investment Hedges (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FinancialinstrumentsandfairvaluemeasurementsDetails" roleURI="http://us.avtr.com/role/FinancialinstrumentsandfairvaluemeasurementsDetails">
        <link:definition>0000061 - Disclosure - Financial instruments and fair value measurements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="avtr_OtherDebtMember" abstract="true" name="OtherDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_AmericasSegmentMember" abstract="true" name="AmericasSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_MediumTermNotes2Point87PercentEUROTermLoanMember" abstract="true" name="MediumTermNotes2Point87PercentEUROTermLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_MediumTermNotes2Point37PercentEUROTermLoanMember" abstract="true" name="MediumTermNotes2Point37PercentEUROTermLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_MediumTermLoanDueNovember82027Abstract" abstract="true" name="MediumTermLoanDueNovember82027Abstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="avtr_EquipmentAndInstrumentationMember" abstract="true" name="EquipmentAndInstrumentationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_SeniorUnsecuredNotes4Point625PercentDueJuly152028Member" abstract="true" name="SeniorUnsecuredNotes4Point625PercentDueJuly152028Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_AdjustedEBITDA" abstract="false" name="AdjustedEBITDA" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="avtr_ProprietaryMaterialsAndConsumablesMember" abstract="true" name="ProprietaryMaterialsAndConsumablesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_ThreePointEightHundredAndSeventyFivePercentUnsecuredMemberMember" abstract="true" name="ThreePointEightHundredAndSeventyFivePercentUnsecuredMemberMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_OtherStockBasedAwardMember" abstract="true" name="OtherStockBasedAwardMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_ServicesAndSpecialtyProcurementMember" abstract="true" name="ServicesAndSpecialtyProcurementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_AmeaMember" abstract="true" name="AmeaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_ForeignCurrencyTransactionGainLossFromFinancingActivities" abstract="false" name="ForeignCurrencyTransactionGainLossFromFinancingActivities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="avtr_ForeignCurrencyDenominatedDebtMember" abstract="true" name="ForeignCurrencyDenominatedDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_MediumTermLoan3Point875PercentDueNovember212024Instrument2Member" abstract="true" name="MediumTermLoan3Point875PercentDueNovember212024Instrument2Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_LineOfCreditFacilityCurrentBorrowingCapacityUpsize" abstract="false" name="LineOfCreditFacilityCurrentBorrowingCapacityUpsize" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="avtr_RitterGmbHMember" abstract="true" name="RitterGmbHMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_TwoPointSixHundredAndTwentyFivePercentSecuredMemberMember" abstract="true" name="TwoPointSixHundredAndTwentyFivePercentSecuredMemberMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_DerivativeNotionalAmountSold" abstract="false" name="DerivativeNotionalAmountSold" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="avtr_EuropeSegmentMember" abstract="true" name="EuropeSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_ThirdPartyMaterialsAndConsumablesMember" abstract="true" name="ThirdPartyMaterialsAndConsumablesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_BusinessCombinationContingentConsiderationPurchaseAccountingAdjustments" abstract="false" name="BusinessCombinationContingentConsiderationPurchaseAccountingAdjustments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="avtr_MediumTermLoan3Point875PercentDueNovember212024Instrument1Member" abstract="true" name="MediumTermLoan3Point875PercentDueNovember212024Instrument1Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_LineOfCreditFacilityCovenantComplianceDrawTriggerPercentage" abstract="false" name="LineOfCreditFacilityCovenantComplianceDrawTriggerPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="avtr_MediumTermNotes2Point25PercentUSDTermLoanMember" abstract="true" name="MediumTermNotes2Point25PercentUSDTermLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="avtr_ProvisionForAccountsReceivableAndInventory" abstract="false" name="ProvisionForAccountsReceivableAndInventory" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="avtr_DerivativesUsedInNetInvestmentHedgeGrossOfTax" abstract="false" name="DerivativesUsedInNetInvestmentHedgeGrossOfTax" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
