A lipase-catalyzed enantioselective hydrolysis process under in situ racemization of the remaining (R)-thioetser substrate with trioctylamine as the catalyst was developed for the production of (S)-fenoprofen from (RS)-fenoprofen 2,2,2-trifluoroethyl thioester in isooctane. Detailed investigations of trioctylamine concentration on the enzyme activation and the kinetic behavior of the thioester in racemization and enzymatic reactions were conducted, in which good agreement between the experimental data and theoretical results was observed.