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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 eRX5bSR7w4maOQyxN8rWHQ==

<SEC-DOCUMENT>0001140361-08-012369.txt : 20080514
<SEC-HEADER>0001140361-08-012369.hdr.sgml : 20080514
<ACCEPTANCE-DATETIME>20080514135148
ACCESSION NUMBER:		0001140361-08-012369
CONFORMED SUBMISSION TYPE:	3/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080131
FILED AS OF DATE:		20080514
DATE AS OF CHANGE:		20080514

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hinckley Robert C
		CENTRAL INDEX KEY:			0001292590

	FILING VALUES:
		FORM TYPE:		3/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12079
		FILM NUMBER:		08830929

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		6503211179

	MAIL ADDRESS:	
		STREET 1:		79 CRESCENT DR.
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94301
</SEC-HEADER>
<DOCUMENT>
<TYPE>3/A
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3/A
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3/A</documentType>

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

    <dateOfOriginalSubmission>2008-02-06</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001292590</rptOwnerCik>
            <rptOwnerName>Hinckley Robert C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>717 TEXAS AVENUE, SUITE 1000</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77002</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>4.75% Contingent Convertible Senior Notes due Nov. 15, 2023</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-11-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, par value $0.001</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Initially convertible into shares of common stock upon the occurrence of certain contingencies. Upon conversion, the number of shares, if any, to be delivered would be determined by calculation of the conversion value based on the conversion rate (initially 153.8462 shares per $1,000 principal amount) and the five day average closing price of the common stock; shares would only be deliverable if the conversion value exceeded the principal amount of the securities converted. In connection with the Issuer's Chapter 11 cases, conversion rights were terminated and, in accordance with the Issuer's Plan of Reorganization, claims in respect of such securities were paid with shares of common stock of the Company. Accordingly, these securities were terminated on January 31, 2008, and on February 6, 2008, a payment of 1,083 shares of common stock was made. It is possible that additional shares of common stock may be payable in respect of such securities pursuant to the Plan of Reorganization.
</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/  Gregory L. Doody by Power of Attorney</signatureName>
        <signatureDate>2008-05-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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