-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001135971-08-000053.txt : 20080401
<SEC-HEADER>0001135971-08-000053.hdr.sgml : 20080401
<ACCEPTANCE-DATETIME>20080401122210
ACCESSION NUMBER:		0001135971-08-000053
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080401
FILED AS OF DATE:		20080401
DATE AS OF CHANGE:		20080401

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PEPCO HOLDINGS INC
		CENTRAL INDEX KEY:			0001135971
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC & OTHER SERVICES COMBINED [4931]
		IRS NUMBER:				522297449
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		SUITE 1300
		STREET 2:		701 NINTH STREET, NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20068
		BUSINESS PHONE:		202-872-2000

	MAIL ADDRESS:	
		STREET 1:		SUITE 1300
		STREET 2:		701 NINTH STREET, NW
		CITY:			WASHINGTON
		STATE:			DC
		ZIP:			20068

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NEW RC INC
		DATE OF NAME CHANGE:	20010302

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Krumsiek Barbara J
		CENTRAL INDEX KEY:			0001399068

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-31403
		FILM NUMBER:		08728186

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		301-951-4887

	MAIL ADDRESS:	
		STREET 1:		CALVERT GROUP, LTD.
		STREET 2:		4550 MONTGOMERY AVENUE
		CITY:			BETHESDA
		STATE:			MD
		ZIP:			20814
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-04-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001135971</issuerCik>
        <issuerName>PEPCO HOLDINGS INC</issuerName>
        <issuerTradingSymbol>POM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001399068</rptOwnerCik>
            <rptOwnerName>Krumsiek Barbara J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>CALVERT GROUP, LTD.</rptOwnerStreet1>
            <rptOwnerStreet2>4550 MONTGOMERY AVENUE</rptOwnerStreet2>
            <rptOwnerCity>BETHESDA</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20814</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-03-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>31.6023</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>31.6023</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3012.8844</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-04-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>858.0658</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>858.0658</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3870.9502</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Acquired in consideration for services, with the number of shares of phantom stock calculated by dividing the amount of meeting fees and/or retainer payable ($2,000 per meeting or that portion of the annual retainer of $85,000 and, if applicable, Committee Chairman annual retainer of either $5,000 or $7,500 and Lead Independent Director annual retainer of $15,000, which the director elected to receive in phantom stock) by the market price of the Pepco Holdings, Inc. (PHI) shares at the close of business two business days before the meeting or retainer payment date, respectively.</footnote>
        <footnote id="F2">Phantom stock on a date specified or to be specified by the participant is settled in cash in an amount equal to the market price of the PHI common stock on the settlement date.</footnote>
        <footnote id="F3">When a dividend is paid on the PHI Common Stock, the Phantom Stock equivalent balance is credited with additional phantom stock based on the number of shares that could be purchased with the cash amount of the dividend at the then current market price.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Barbara J. Krumsiek by Ellen Sheriff Rogers, Attorney-in-Fact</signatureName>
        <signatureDate>2008-04-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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