Novel sulfonated poly(arylene ether sulfone) polymers with 3,4-difluoro-phenyl group (2F-SPAES-xx) were successfully synthesiZed via the direct copolymerization of 3,3'-disulfonate-4,4'-dichlorodiphenylsulfone, 4,4-dichlorodiphenylsUlfone and 3,4-difluoro-phenyl hydroquinone. The polymers with different sulfonation degree were prepared by changing the mole ratio (20%-40%) of sulfonated monomer in the polymerization reaction. The proton conductivity, thermal and oxidative stability, mechanical properties, water uptake, swelling ratio, phase separated morphology of the membranes were explored. The 2F-SPAES-40 membrane showed higher proton conductivity and better phase separation, oxidative stability than that of sulfonated poly(arylene ether sulfone) membrane (SPAES-6FPA-40). The proton conductivity of 2F-SPAES-40 membrane Was up to 0.142 Scm(-1) at 80 degrees C in wet. These results indicated that incorporation of hydrophobic 3,4-difluoro-phenyl side group enhanced the oxidative stability and improved the proton conductivity by promoting the phase separation. (C) 2016 Elsevier B.V. All rights reserved.