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                          June 7, 2024

       David Stasse
       Chief Financial Officer
       Trinseo PLC
       440 East Swedesford Road, Suite 301
       Wayne, PA 19087

                                                        Re: Trinseo PLC
                                                            Form 10-K for the 
Year Ended December 31, 2023
                                                            File No. 001-36473

       Dear David Stasse:

              We have reviewed your June 5, 2024 response to our comment letter 
and have the
       following comment.

              Please respond to this letter within ten business days by 
providing the requested
       information or advise us as soon as possible when you will respond. If 
you do not believe a
       comment applies to your facts and circumstances, please tell us why in 
your response.

               After reviewing your response to this letter, we may have 
additional comments. Unless
       we note otherwise, any references to prior comments are to comments in 
our May 29, 2024
       letter.

       Form 10-K for the Year Ended December 31, 2023

       Financial Statements, page F-1

   1.                                                   We note your response 
to comment 1. Please provide us with the calculations and
                                                        corresponding 
explanations which led to your determination that Americas Styrenics LLC
                                                        was not significant in 
any period presented pursuant to Rule 3-09 and Rule 1-02(w) of
                                                        Regulation S-X.
 David Stasse
Trinseo PLC
June 7, 2024
Page 2

       Please contact Nudrat Salik at 202-551-3692 or Jeanne Baker at 
202-551-3691 if you
have questions regarding comments on the financial statements and related 
matters.



                                                         Sincerely,
FirstName LastNameDavid Stasse
                                                         Division of 
Corporation Finance
Comapany NameTrinseo PLC
                                                         Office of Industrial 
Applications and
June 7, 2024 Page 2                                      Services
FirstName LastName