<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-12-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001262200</issuerCik>
        <issuerName>DAYSTAR TECHNOLOGIES INC</issuerName>
        <issuerTradingSymbol>DSTI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000704159</rptOwnerCik>
            <rptOwnerName>PAULSON CAPITAL CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>811 SW NAITO PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PORTLAND</rptOwnerCity>
            <rptOwnerState>OR</rptOwnerState>
            <rptOwnerZipCode>97204</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Footnote (1)</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000898196</rptOwnerCik>
            <rptOwnerName>PAULSON CHESTER L F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>811 SW NAITO PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PORTLAND</rptOwnerCity>
            <rptOwnerState>OR</rptOwnerState>
            <rptOwnerZipCode>97204</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Footnote (1)</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000897686</rptOwnerCik>
            <rptOwnerName>PAULSON JACQUELINE M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>811 SW NAITO PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PORTLAND</rptOwnerCity>
            <rptOwnerState>OR</rptOwnerState>
            <rptOwnerZipCode>97204</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Footnote (1)</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Class B Warrants (Right to buy Common Stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>10.00</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-12-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.255</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-02-05</value>
            </exerciseDate>
            <expirationDate>
                <value>2009-02-05</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>935156</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Form filed by more than one reporting person.  In addition to Paulson Capital Corp. (&quot;PLCC&quot;), the following are reporting parties:  Chester L.F. Paulson, Jacqueline M. Paulson, Paulson Family LLC (&quot;LLC&quot;) and Paulson Investment Company, Inc. (&quot;PICI).  Mr. and Mrs. Paulson are controlling managers of the LLC, which is a controlling shareholder of PLCC, which is the parent company of PICI.  Mr. and Mrs. Paulson and the LLC expressly disclaim any beneficial ownership of securities held in the name of PLCC and PICI.</footnote>
        <footnote id="F2">Of the nine hundred thirty five thousand one hundred fifty six (935,1560) number of securities, three hundred seventy thousand (370,000) are class B warrants and the remainder consist of one hundred forty one thousand two hundred eighty nine (141,289) underwriter warrants.  One (1) underwriter warrant is exercisable into One (1) Daystar Technologies, Inc. Unit which consist of one (1) share of common stock, one (1) share of class A warrant, and two (2) shares of class B warrants.  One (1) class A warrant is then exercisable at $6.00 into one (1) share of common stock.  One (1) class B warrant is exercisable at $10.00 into one (1) share of Common Stock.  Both class A &amp; B warrants expire February 5, 2009.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Harry L. Striplin, Attorney-in-Fact for Chester L.F. Paulson</signatureName>
        <signatureDate>2004-12-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Harry L. Striplin, Authorized Agent for Paulson Capital Corp.</signatureName>
        <signatureDate>2004-12-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Harry L. Striplin, Authorized Agent for Paulson Investment Co., Inc.</signatureName>
        <signatureDate>2004-12-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Harry L. Striplin, Authorized Agent for Paulson Family LLC</signatureName>
        <signatureDate>2004-12-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Harry L. Striplin, Attorney-in-Fact for Jacqueline M. Paulson</signatureName>
        <signatureDate>2004-12-28</signatureDate>
    </ownerSignature>
</ownershipDocument>

