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      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001941417</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0000003197</issuerCik>
        <issuerName>CECO ENVIRONMENTAL CORP</issuerName>
        <secFileNumber>000-07099</secFileNumber>
        <issuerAddress>
          <com:street1>5080 SPECTRUM DRIVE</com:street1>
          <com:street2>SUITE 800E</com:street2>
          <com:city>ADDISON</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>75001</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>(513) 458-2600</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Johansson Peter K.</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>900 Salem Street</com:street1>
            <com:city>Smithfield</com:city>
            <com:stateOrCountry>RI</com:stateOrCountry>
            <com:zipCode>02917</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>22500</noOfUnitsSold>
        <aggregateMarketValue>512933.77</aggregateMarketValue>
        <noOfUnitsOutstanding>34989986</noOfUnitsOutstanding>
        <approxSaleDate>03/31/2025</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>12/29/2023</acquiredDate>
        <natureOfAcquisitionTransaction>ESPP Purchase</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>517</amountOfSecuritiesAcquired>
        <paymentDate>12/29/2023</paymentDate>
        <natureOfPayment>Cash</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>03/31/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1759</amountOfSecuritiesAcquired>
        <paymentDate>03/31/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>06/28/2024</acquiredDate>
        <natureOfAcquisitionTransaction>ESPP Purchase</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>589</amountOfSecuritiesAcquired>
        <paymentDate>06/28/2024</paymentDate>
        <natureOfPayment>Cash</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>08/15/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>4860</amountOfSecuritiesAcquired>
        <paymentDate>08/15/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>03/15/2025</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>14775</amountOfSecuritiesAcquired>
        <paymentDate>03/15/2025</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Peter Johansson</name>
          <address>
            <com:street1>5080 Spectrum Drive</com:street1>
            <com:street2>Suite 800E</com:street2>
            <com:city>Addison</com:city>
            <com:stateOrCountry>TX</com:stateOrCountry>
            <com:zipCode>75001</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>03/27/2025</saleDate>
        <amountOfSecuritiesSold>5601</amountOfSecuritiesSold>
        <grossProceeds>135264.15</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>03/31/2025</noticeDate>
        <signature>/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Peter Johansson</signature>
      </noticeSignature>
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text: 144
  0001941417
  XXXXXXXX
  LIVE
  0000003197
  CECO ENVIRONMENTAL CORP
  000-07099
  5080 SPECTRUM DRIVE
  SUITE 800E
  ADDISON
  TX
  75001
  (513) 458-2600
  Johansson Peter K.
  Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  22500
  512933.77
  34989986
  03/31/2025
  NASDAQ
  Common
  12/29/2023
  ESPP Purchase
  Issuer
  N
  517
  12/29/2023
  Cash
  Common
  03/31/2024
  Restricted Stock Vesting
  Issuer
  N
  1759
  03/31/2024
  Compensation
  Common
  06/28/2024
  ESPP Purchase
  Issuer
  N
  589
  06/28/2024
  Cash
  Common
  08/15/2024
  Restricted Stock Vesting
  Issuer
  N
  4860
  08/15/2024
  Compensation
  Common
  03/15/2025
  Restricted Stock Vesting
  Issuer
  N
  14775
  03/15/2025
  Compensation
  N
  Peter Johansson
  5080 Spectrum Drive
  Suite 800E
  Addison
  TX
  75001
  Common
  03/27/2025
  5601
  135264.15
  03/31/2025
  /s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Peter Johansson