Four aromatic poly(ether sulfone)s (PESs) based on (3-niethyl)phenylhydroquinone. (3-trifluoromethyl)plienylhydroquinone, (3,5-dimethyl)phenyIhydroquinone, and (3,5-ditrifluoromethyl)phenylhydroquinone were prepared via a nucleophilic aromatic substitution polycondensation with bis(4-fluorophenyl) sulfone. These PESs had a high thermal stability with a 5% weight loss above 423degreesC in N-2. The PESs possessed good solubility in common organic solvents. All the polymers formed transparent and flexible films using solution casting method. The dielectric constants estimated from refractive indices of the PES films are 2.64-3.07. Compared with the corresponding methylated PESs, the trifluoromethylated PESs exhibited low glass transition temperatures, higher thermal decomposition temperatures, and low dielectric constants.