Novel sulphonated poly(ether ether sulphone) copolymers were synthesised by polycondensation reaction of stoichiometric amounts of silylated hydroquinone sulphonic acid, 4,4'-difluorodiphenyl sulphone and bisphenols, i.e., bisphenol-A, 4,4'-dihydroxybiphenyl, hydroquinone, phenolphthalein and 2,6-dihydroxynaphthalene. The structure of the copolymers was confirmed by using ATR-FTIR, H-1 NMR and C-13 NMR techniques. Number average molecular weight (GPC) of the polymers was in the range of 7900-18,000 g/mol. The water uptake of polymer films prepared by casting technique depended on the backbone structure and degree of sulphonation. The proton conductivity of these membranes at room temperature was in the range of 3.3 x 10(-3)-6.1 X 10(-6) S/CM. (c) 2005 Elsevier B.V. All rights reserved.