Novel aromatic sulfonated poly(ether ether sulfone)s (SPEESs) with tert-butyl groups were synthesized by aromatic nucleophilic polycondensation of disodium 3,3'-disuffonate-4,4'-dichlorodiphenylsulfone (SDCDPS), 4,4'-dichlorodiphenylsulfone (DCDPS), and tert-butylhydroquinone (TBHQ). The resulting copolymers showed very good thermal stability and could be cast into tough membranes. The morphology of the membranes was investigated with atomic force microscopy. The proton conductivity of SPEES-40 membranes increased from 0.062 S/cm at 25 degrees C to 0.083 S/cm at 80 degrees C, which was higher than the 0.077 S/cm of Nafion 117 under the same testing conditions. These copolymers are good candidates to be new polymeric electrolyte materials for proton exchange membrane fuel cells. (c) 2007 Wiley Periodicals, Inc.