-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 JZ8/CIABKz0YXtkq2E41o7Abxo9zg1I5y+e2MK30/ntXI6QeqJ9WtIGr5a56P84w
 1Eo9fJR6tdZ3HkgeI9RmsA==

<SEC-DOCUMENT>0001492661-10-000008.txt : 20101112
<SEC-HEADER>0001492661-10-000008.hdr.sgml : 20101111
<ACCEPTANCE-DATETIME>20101112101135
ACCESSION NUMBER:		0001492661-10-000008
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101110
FILED AS OF DATE:		20101112
DATE AS OF CHANGE:		20101112

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Killion Richard L
		CENTRAL INDEX KEY:			0001492661

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34658
		FILM NUMBER:		101183652

	MAIL ADDRESS:	
		STREET 1:		13024 BALLANTYNE CORPORATE PLACE
		STREET 2:		SUITE 700
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28277

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Babcock & Wilcox Co
		CENTRAL INDEX KEY:			0001486957
		STANDARD INDUSTRIAL CLASSIFICATION:	ENGINES & TURBINES [3510]
		IRS NUMBER:				800558025
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		13024 BALLANTYNE CORPORATE PLACE
		STREET 2:		SUITE 700
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28277
		BUSINESS PHONE:		434-522-6800

	MAIL ADDRESS:	
		STREET 1:		13024 BALLANTYNE CORPORATE PLACE
		STREET 2:		SUITE 700
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28277
</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>2010-11-10</periodOfReport>

    <issuer>
        <issuerCik>0001486957</issuerCik>
        <issuerName>Babcock &amp; Wilcox Co</issuerName>
        <issuerTradingSymbol>BWC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001492661</rptOwnerCik>
            <rptOwnerName>Killion Richard L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>13024 BALLANTYNE CORPORATE PLACE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 700</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28277</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President - PGG</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-11-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1469</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22966</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>1873</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401k Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Based on number of units held in the BWC Thrift Plan and the fair market value of BWC common stock as of November 10, 2010.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Angela P. Winter, attorney-in-fact</signatureName>
        <signatureDate>2010-11-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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