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        <filerCredentials>
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          <ccc>XXXXXXXX</ccc>
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      <liveTestFlag>LIVE</liveTestFlag>



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      <issuerCik>0000097745</issuerCik>
      <issuerName>THERMO FISHER SCIENTIFIC INC.</issuerName>
      <secFileNumber>001-08002</secFileNumber>
      <issuerAddress>
        <com:street1>168 THIRD AVENUE</com:street1>
        <com:city>WALTHAM</com:city>
        <com:stateOrCountry>MA</com:stateOrCountry>
        <com:zipCode>02451</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>7816221000</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Williamson Stephen</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>14100</noOfUnitsSold>
      <aggregateMarketValue>7755000.00</aggregateMarketValue>
      <noOfUnitsOutstanding>385721286</noOfUnitsOutstanding>
      <approxSaleDate>08/01/2023</approxSaleDate>
      <securitiesExchangeName>NYSE</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>08/01/2023</acquiredDate>
      <natureOfAcquisitionTransaction>Option Granted - 09/07/2017</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>14100</amountOfSecuritiesAcquired>
      <paymentDate>08/01/2023</paymentDate>
      <natureOfPayment>Cash</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
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      <sellerDetails>
        <name>Stephen Williamson</name>
        <address>
          <com:street1>168 Third Avenue</com:street1>
          <com:city>Waltham</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02451</com:zipCode>
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      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>07/31/2023</saleDate>
      <amountOfSecuritiesSold>15000</amountOfSecuritiesSold>
      <grossProceeds>8361300.00</grossProceeds>
    </securitiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>08/01/2023</noticeDate>
      <planAdoptionDates>
        <planAdoptionDate>09/01/2022</planAdoptionDate>
      </planAdoptionDates>
      <signature>/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Stephen Williamson</signature>
    </noticeSignature>
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144
0001648929
XXXXXXXX
LIVE
0000097745
THERMO FISHER SCIENTIFIC INC.
001-08002
168 THIRD AVENUE
WALTHAM
MA
02451
7816221000
Williamson Stephen
Officer
Common
Fidelity Brokerage Services LLC
900 Salem Street
Smithfield
RI
02917
14100
7755000.00
385721286
08/01/2023
NYSE
Common
08/01/2023
Option Granted - 09/07/2017
Issuer
N
14100
08/01/2023
Cash
N
Stephen Williamson
168 Third Avenue
Waltham
MA
02451
Common
07/31/2023
15000
8361300.00
08/01/2023
09/01/2022
/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Stephen Williamson