The cross-linkable sulfonated ploy(arylene ether)s derived from 3,3'-diallyl-4,4'-dihydroxybiphenyl, bisphthalazinone, 4,4-difluorobenzophenone (DFBP) and sulfonated 4,4'-diflourobenzophenone (SDFBP) were synthesized over a wide range of DFBP/SDFBP molar ratios. The resulting sulfonated poly(arylene ether)s with high inherent viscosity (1.02-1.29 dL g(-1)) are soluble in polar organic solvents and can form flexible and transparent membranes by casting from their solution. Cross-linking reaction was carried out using the thermal activated radical cross-linking agent (TARC) at 140 degrees C. The comprehensive properties of the virgin and the cross-linked membranes were compared accordingly. The results showed that the cross-linked membranes revealed the better mechanical, oxidative and dimensional stabilities together with high proton conductivity (9.675 x 10(-3) S cm(-1)) at 25 degrees C under 100% relative humidity. (c) 2006 Elsevier B.V. All rights reserved.