<SUBMISSION>
<ACCESSION-NUMBER>0001181431-08-059044
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20081028
<FILING-DATE>20081030
<DATE-OF-FILING-DATE-CHANGE>20081030
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SPO ADVISORY PARTNERS LP
<CIK>0001252456
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>081152358
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>STE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SAN FRANCISCO PARTNERS II LP
<CIK>0001252458
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
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<FILING-VALUES>
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<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>STE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SF ADVISORY PARTNERS LP
<CIK>0000948279
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
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<FILING-VALUES>
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<FILM-NUMBER>081152357
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<BUSINESS-ADDRESS>
<STREET1>591 REDWOOD HWY
<STREET2>STE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY STE 3215
<STREET2>C/O SPO PARTNERS & CO
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SPO ADVISORY CORP
<CIK>0000919468
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
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<FILM-NUMBER>081152359
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>SUITE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
<PHONE>4153836600
</BUSINESS-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>SF ADVISORY CORP
<DATE-CHANGED>19990329
</FORMER-NAME>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CALPINE CORP
<CIK>0000916457
<ASSIGNED-SIC>4911
<IRS-NUMBER>770212977
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>50 WEST SAN FERNANDO ST
<CITY>SAN JOSE
<STATE>CA
<ZIP>95113
<PHONE>4089955115
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>50 W SAN FERNANDO
<STREET2>SUITE 500
<CITY>SAN JOSE
<STATE>CA
<ZIP>95113
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SPO PARTNERS II LP
<CIK>0001046206
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>081152362
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY STE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
<PHONE>4153836600
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY, 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>MAIN STREET PARTNERS LP
<DATE-CHANGED>19970916
</FORMER-NAME>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SPO Partners II Co Investment Partnership LP
<CIK>0001398581
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>081152360
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>591 Redwood Highway
<STREET2>Ste 3215
<CITY>Mill Valley
<STATE>CA
<ZIP>94941
<PHONE>4153836600
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>591 Redwood Highway
<STREET2>Ste 3215
<CITY>Mill Valley
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd221807.xml
<DESCRIPTION>STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-10-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000916457</issuerCik>
        <issuerName>CALPINE CORP</issuerName>
        <issuerTradingSymbol>CPN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000919468</rptOwnerCik>
            <rptOwnerName>SPO ADVISORY CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252456</rptOwnerCik>
            <rptOwnerName>SPO ADVISORY PARTNERS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000948279</rptOwnerCik>
            <rptOwnerName>SF ADVISORY PARTNERS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY , SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001046206</rptOwnerCik>
            <rptOwnerName>SPO PARTNERS II LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252458</rptOwnerCik>
            <rptOwnerName>SAN FRANCISCO PARTNERS II LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001398581</rptOwnerCik>
            <rptOwnerName>SPO Partners II Co Investment Partnership LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-10-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>455305</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.73</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>92716166</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The entities directly acquiring the shares reported in this filing and related filings today are SPO Partners II, L.P. (&quot;SPO Partners&quot;), which bought 382,305 shares,the Elizabeth R. &amp; William J. Patterson Foundation (&quot;WJPFND&quot;) which bought 68,400 shares, and Edward H. McDermott (&quot;EHM&quot;) who bought 4,600 shares.  The range of prices for the purchases on 10/28/08, reported in Line 1 above, was $10.46-$11.41.(full detailed information regarding the shares purchased at each price will be provided upon request ).</footnote>
        <footnote id="F2">As a result of the purchases causing this filing and related filings today, and as a result of the conversion of debt instruments to common stock upon the issuer's emergence from bankruptcy,84,360,913 shares are owned directly by SPO Partners, and may be deemed to be indirectly beneficially owned by (i) SPO Advisory Partners, L.P. (&quot;SPO Advisory&quot;), the sole general partner of SPO Partners, (ii) SPO Advisory Corp. (&quot;SPO Corp.&quot;), the sole general partner of SPO Advisory, and (iii) John H. Scully (&quot;JHS&quot;), William E. Oberndorf (&quot;WEO&quot;), William J. Patterson (&quot;WJP&quot;) &amp; EHM, the four controlling persons of SPO Corp. Additionally, 5,150,500 shares are owned directly by SPO Partners II Co-Investment Partnership, L.P. (&quot;SPO Co-Invest&quot;), and may be deemed to be indirectly beneficially owned by (i) SPO Advisory, the sole general partner of SPO Co-Invest, (ii) SPO Corp, the sole general partner of SPO Advisory, and (iii) JHS, WEO, WJP and EHM, the four controlling persons of SPO Corp.</footnote>
        <footnote id="F3">Additionally, 3,204,753 shares are owned directly by San Francisco Partners II, L.P. (&quot;SF Partners&quot;), and may be deemed to be indirectly beneficially owned by (i) SF Advisory Partners, L.P. (&quot;SF Advisory&quot;), the sole general partner of SF Partners, (ii)SPO Corp., the sole general partner of SF Advisory, and (iii)JHS, WEO, WJP and EHM, the four controlling persons of SPO Corp.  Additionally, as a result of the purchases causing this filing and related filings today, WJPFND owns 129,900 shares, JHS owns 6,100 shares in his IRAs, which are self-directed, WEO owns 34,900 shares in his IRA, which is self-directed, WJP owns 1,600 shares in his IRA, which is self-directed and EHM owns 6,800 shares in his IRA, which is self-directed.</footnote>
        <footnote id="F4">Additionally, 5,029 shares of restricted stock and 2,720 restricted stock units are owned by WJP, a director of the Issuer.  Pursuant to the partnership agreement governing SPO Partners, these shares may be deemed to be indirectly beneficially owned by SPO Partners together with any profits arising therefrom.</footnote>
        <footnote id="F5">Additionally, the shares represented in Column 5 above may be deemed to be indirectly beneficially owned by J. Stuart Ryan (&quot;JSR&quot;), solely in his advisory capacity to SPO Corp.  Additionally, 5,029 shares of restricted stock are owned by JSR, a director of the Issuer.</footnote>
    </footnotes>

    <remarks>Form 1 of 2.

The individuals listed in the notes above (each a ?Reporting Person?) may be deemed to form a ?group?, as such term is defined in Rule 13d-5(b)(1) promulgated under the Securities Exchange Act of 1934, for purposes of this filing.  This filing shall not be deemed as an admission by any Reporting Person that such person is, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the beneficial owner of any equity securities covered by this statement.  Each Reporting Person disclaims beneficial ownership of the reported securities except to the extent of such person?s pecuniary interest, if any, therein.</remarks>

    <ownerSignature>
        <signatureName>Kim M. Silva, Attorney-in-Fact</signatureName>
        <signatureDate>2008-10-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SUBMISSION>
