-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 CbGhOuww/hDmFvCLngj5vm9gQhwqvexCU+ICQC/8HoITpAeeW7k3aNhFH5Gac7yR
 usa/8gwFXpZzJGE8EBTTFg==

<SEC-DOCUMENT>0001140361-08-002708.txt : 20080204
<SEC-HEADER>0001140361-08-002708.hdr.sgml : 20080204
<ACCEPTANCE-DATETIME>20080204170959
ACCESSION NUMBER:		0001140361-08-002708
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080131
FILED AS OF DATE:		20080204
DATE AS OF CHANGE:		20080204

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DOODY GREGORY L
		CENTRAL INDEX KEY:			0001264984

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12079
		FILM NUMBER:		08573109

	BUSINESS ADDRESS:	
		STREET 1:		4603 CLAIRMONT AVE
		CITY:			BIRMINGHAM
		STATE:			AL
		ZIP:			35222
		BUSINESS PHONE:		2059705917

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CALPINE CORP
		CENTRAL INDEX KEY:			0000916457
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC SERVICES [4911]
		IRS NUMBER:				770212977
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		50 WEST SAN FERNANDO ST
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95113
		BUSINESS PHONE:		4089955115

	MAIL ADDRESS:	
		STREET 1:		50 W SAN FERNANDO
		STREET 2:		SUITE 500
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95113
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-01-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001264984</rptOwnerCik>
            <rptOwnerName>DOODY GREGORY L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>CALPINE CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>717 TEXAS AVE</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77002</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, General Counsel &amp;  Secty</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Non-Qualified Stock Option (Right to Buy)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>16.90</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-01-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>64100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2010-07-31</value>
            </exerciseDate>
            <expirationDate>
                <value>2018-01-31</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>64100</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>64100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Grant of option pursuant to the Issuer's 2008 Equity Incentive Plan.  The option becomes exercisable in two equal installments over three years. 50% of the award vests 18 months after the grant date and 100% of the balance of the award vests 36 months after the grant date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By:   Gregory L. Doody</signatureName>
        <signatureDate>2008-02-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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