High molecular weight poly(arylene thioether)s containing trifluoromethyl groups were prepared through the aromatic nucleophilic nitro-displacement reaction of a dinitro monomer with aromatic dithiols. The high reactivity of the monomer, 4,4'-dinitro-3,3'-bis(trifluoromethyl)biphenyl(l), activated by o-trifluoromethyl groups and complete exclusion of oxygen was critical for the successful polymerization without any disulfide formation. The resulting trifluoromethylated poly(arylene thioether)s (P1 and P2) were amorphous, dissolved in common organic solvents, and showed superior thermal properties compared to commercial poly(phenylene sulfide). (c) 2006 Wiley Periodicals, Inc.