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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001140361-08-009754.txt : 20080417
<SEC-HEADER>0001140361-08-009754.hdr.sgml : 20080417
<ACCEPTANCE-DATETIME>20080417175111
ACCESSION NUMBER:		0001140361-08-009754
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080415
FILED AS OF DATE:		20080417
DATE AS OF CHANGE:		20080417

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			DYNEGY INC.
		CENTRAL INDEX KEY:			0001379895
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC SERVICES [4911]
		IRS NUMBER:				205653152
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1000 LOUISIANA STREET, SUITE 5800
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002
		BUSINESS PHONE:		(713) 507-6400

	MAIL ADDRESS:	
		STREET 1:		1000 LOUISIANA STREET, SUITE 5800
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Dynegy Inc..
		DATE OF NAME CHANGE:	20070404

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Dynegy Acquisition, Inc..
		DATE OF NAME CHANGE:	20070403

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Dynegy Acquisition, Inc.
		DATE OF NAME CHANGE:	20061102

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MAZANEC GEORGE L
		CENTRAL INDEX KEY:			0001212331

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33443
		FILM NUMBER:		08762955

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		7162848897

	MAIL ADDRESS:	
		STREET 1:		MAID OF THE MIST CORP
		STREET 2:		151 BUFFALO AVE.
		CITY:			NIAGARA FALLS
		STATE:			NY
		ZIP:			14303
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-04-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001379895</issuerCik>
        <issuerName>DYNEGY INC.</issuerName>
        <issuerTradingSymbol>DYN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001212331</rptOwnerCik>
            <rptOwnerName>MAZANEC GEORGE L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1000 LOUISIANA</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 5800</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77002</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-04-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2218</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2218</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40880.97</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These shares of phantom stock are convertible on a 1-for-1 basis.</footnote>
        <footnote id="F2">Reflects shares of phantom stock issued to the Reporting Person pursuant to the Dynegy Inc. Deferred Compensation Plan for Certain Directors, as amended, a Rule 16b-3 Plan with the issuer.  The shares of phantom stock were issued in connection with the Reporting Person's director compensation for the first quarter of 2008, and the number of shares issued with respect to the quarter was calculated based on the closing price of the issuer's Class A common stock of $7.89 on March 31, 2008, the last trading day of the quarter.</footnote>
        <footnote id="F3">Upon termination of the Reporting Person's service as a director, the shares of phantom stock become payable, at the election of the Reporting Person, in a lump sum payment or in monthly, quarterly or annual installment payments following such termination.  The shares of phantom stock are payable in cash or in shares of the issuer's Class A common stock.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Heidi D. Lewis, Attorney-in-Fact</signatureName>
        <signatureDate>2008-04-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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