-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 ARQH8a/olBLrdwS6CYm4awWzeFPIxVsjpzy8TOJfeSl5aBT5eio18Lus8JZO5peG
 x1UKN2zDc4qYWlsyl+IXaA==

<SEC-DOCUMENT>0001179110-04-002802.txt : 20040209
<SEC-HEADER>0001179110-04-002802.hdr.sgml : 20040209
<ACCEPTANCE-DATETIME>20040209151507
ACCESSION NUMBER:		0001179110-04-002802
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040209
FILED AS OF DATE:		20040209

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SINGER KAREN M
		CENTRAL INDEX KEY:			0001250529

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14023
		FILM NUMBER:		04577538

	BUSINESS ADDRESS:	
		STREET 1:		CORPORATE OFFICE PROPERTIES TR
		STREET 2:		8815 CENTRE PARK DR STE 400
		CITY:			COLUMBIA
		STATE:			MD
		ZIP:			21045
		BUSINESS PHONE:		4109927293

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CORPORATE OFFICE PROPERTIES TRUST
		CENTRAL INDEX KEY:			0000860546
		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
		IRS NUMBER:				232947217
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		8815 CENTRE PARK DR
		STREET 2:		SUITE 400
		CITY:			COLUMBIA
		STATE:			MD
		ZIP:			21045
		BUSINESS PHONE:		6105381800

	MAIL ADDRESS:	
		STREET 1:		8815 CENTRE PARK DR
		STREET 2:		SUITE 400
		CITY:			COLUMBIA
		STATE:			MD
		ZIP:			21045

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CORPORATE OFFICE PROPERTIES TRUST INC
		DATE OF NAME CHANGE:	19980105

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ROYALE INVESTMENTS INC
		DATE OF NAME CHANGE:	19930328

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ROYALE REIT INC
		DATE OF NAME CHANGE:	19600201
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 3 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2004-02-09</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000860546</issuerCik>
        <issuerName>CORPORATE OFFICE PROPERTIES TRUST</issuerName>
        <issuerTradingSymbol>OFC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001250529</rptOwnerCik>
            <rptOwnerName>SINGER KAREN M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>11741 GREENSPRING AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LUTHERVILLE</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>21093</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, General Counsel &amp; Sec</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>200</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4818</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2202</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Acquire Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>8.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-06-01</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2009-06-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Options to Acquire Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Acquire Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>8.625</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-05-30</value>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2010-05-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Options to Acquire Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Acquire Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.54</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-01-29</value>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2011-01-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Options to Acquire Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Acquire Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.87</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2002-01-01</value>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-01-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Options to Acquire Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Options to Acquire Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>20.34</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2005-01-01</value>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-01-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Options to Acquire Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted Stock granted on 1/31/03, which vests on annual basis starting on first anniversary of grant and for four years thereafter in the following percentages:  16%, 18%, 20%, 22% and 24%.</footnote>
        <footnote id="F2">Restricted Stock granted on 1/31/04, which vests on annual basis starting on first anniversary of grant and for four years thereafter in the following percentages:  16%, 18%, 20%, 22% and 24%.</footnote>
        <footnote id="F3">All Options fully vested as of 6/1/02.</footnote>
        <footnote id="F4">All options fully vested as of 1/29/04</footnote>
        <footnote id="F5">All Options fully vested as of 5/30/03</footnote>
        <footnote id="F6">6,250 Options vested on the date of grant and balance of Options vest on each anniversary thereafter in the amount of 6,250 Options per year.</footnote>
        <footnote id="F7">Options vest in thirds (2,500 options per year) commencing on the first anniversary of the grant</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Karen Miller Singer</signatureName>
        <signatureDate>2004-02-09</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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