-----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,
 MVFJDq7SM0nkUoxoTmvsqkbQSiU81NSbohlsLCM/h68RrvYBJ4ZAlHOhVAAXcds/
 M0l13DkaII6t2jbD0GUQbA==

<SEC-DOCUMENT>0001140361-10-050997.txt : 20101222
<SEC-HEADER>0001140361-10-050997.hdr.sgml : 20101222
<ACCEPTANCE-DATETIME>20101222144856
ACCESSION NUMBER:		0001140361-10-050997
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101221
FILED AS OF DATE:		20101222
DATE AS OF CHANGE:		20101222

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kruger Logan W
		CENTRAL INDEX KEY:			0001344865

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34474
		FILM NUMBER:		101268321

	MAIL ADDRESS:	
		STREET 1:		C/O CENTURY ALUMINUM COMPANY
		STREET 2:		2511 GARDEN ROAD, BUILDING A, SUITE 200
		CITY:			MONTEREY
		STATE:			CA
		ZIP:			93940

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CENTURY ALUMINUM CO
		CENTRAL INDEX KEY:			0000949157
		STANDARD INDUSTRIAL CLASSIFICATION:	PRIMARY PRODUCTION OF ALUMINUM [3334]
		IRS NUMBER:				133070826
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2511 GARDEN ROAD
		STREET 2:		BUILDING A SUITE 200
		CITY:			MONTEREY
		STATE:			CA
		ZIP:			93940
		BUSINESS PHONE:		3042736000

	MAIL ADDRESS:	
		STREET 1:		2511 GARDEN ROAD
		STREET 2:		BUILDING A SUITE 200
		CITY:			MONTEREY
		STATE:			CA
		ZIP:			93940
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-12-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000949157</issuerCik>
        <issuerName>CENTURY ALUMINUM CO</issuerName>
        <issuerTradingSymbol>CENX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001344865</rptOwnerCik>
            <rptOwnerName>Kruger Logan W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>CENTURY ALUMINUM COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>2511 GARDEN ROAD, BLDG A, SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>MONTEREY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93940</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-12-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>16.15</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>207422</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>224.3216</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the average sale price of 10,000 shares in six separate transactions at prices ranging from $16.140 to $16.161. Upon the request of the Securities and Exchange Commission (SEC), the Reporting Person will provide the SEC with full information regarding the number of shares and prices at which the transactions were effected.</footnote>
        <footnote id="F2">Includes unvested shares of performance share units granted to the Reporting Person in connection with the Issuer's 2008-2010, 2009-2011 and 2010-2012 Performance Share Program Periods under a rule 16(b)-3(d) plan, all of which vest in the ordinary course on December 31, 2010, January 1, 2011 and December 31, 2012, respectively.</footnote>
        <footnote id="F3">Reported by 401(k) plan trustee on December 20, 2010.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jesse E. Gary, Attorney-in-Fact for Logan W. Kruger</signatureName>
        <signatureDate>2010-12-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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