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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
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 Yzimg28WkzVjWLNWLazNuQ==

<SEC-DOCUMENT>0000950103-10-001512.txt : 20100520
<SEC-HEADER>0000950103-10-001512.hdr.sgml : 20100520
<ACCEPTANCE-DATETIME>20100520102754
ACCESSION NUMBER:		0000950103-10-001512
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100519
FILED AS OF DATE:		20100520
DATE AS OF CHANGE:		20100520

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Bryant Joseph H
		CENTRAL INDEX KEY:			0001295907

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34579
		FILM NUMBER:		10846891

	MAIL ADDRESS:	
		STREET 1:		COBALT INTERNATIONAL ENERGY, INC.
		STREET 2:		1980 POST OAK BOULEVARD, SUITE 1200
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77056

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Cobalt International Energy, Inc.
		CENTRAL INDEX KEY:			0001471261
		STANDARD INDUSTRIAL CLASSIFICATION:	CRUDE PETROLEUM & NATURAL GAS [1311]
		IRS NUMBER:				270821169
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		TWO POST OAK CENTRAL
		STREET 2:		1980 POST OAK BOULEVARD, SUITE 1200
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77056
		BUSINESS PHONE:		(713) 579-9101

	MAIL ADDRESS:	
		STREET 1:		TWO POST OAK CENTRAL
		STREET 2:		1980 POST OAK BOULEVARD, SUITE 1200
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77056
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-05-19</periodOfReport>

    <issuer>
        <issuerCik>0001471261</issuerCik>
        <issuerName>Cobalt International Energy, Inc.</issuerName>
        <issuerTradingSymbol>CIE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001295907</rptOwnerCik>
            <rptOwnerName>Bryant Joseph H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TWO POST OAK CENTRAL</rptOwnerStreet1>
            <rptOwnerStreet2>1980 POST OAK BOULEVARD, SUITE 1200</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77056</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman of the Board and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-05-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.93</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4848387</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>506152</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This purchase price is a weighted average purchase price that represents the purchase of these shares of Common Stock at prices ranging from $8.88 to $8.95.  The reporting person undertakes to provide upon request by the SEC staff, the Issuer or any security holder of the Issuer, full information regarding the number of shares of Common Stock sold at each separate price.</footnote>
        <footnote id="F2">These shares of Common Stock are directly owned by the Bryant 2007 Descendants' Trust for the benefit of the reporting person's minor children.  The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jeffrey A. Starzec, Attorney-in-Fact</signatureName>
        <signatureDate>2010-05-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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