Novel bisphenol-based wholly aromatic poly(ether sulfone-ketone) copolymer containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of 4,4-difluorobenzophenone, 2,2'-disodiumsulfonyl-4,4'-fluorophenylsulfone (40mole% of bisphenol A) and bisphenol A. Polymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at . Organic-inorganic composite membranes were obtained by mixing organic polymers with hydrophilic (ca. 20nm) obtained by sol-gel process. The polymer and a series of composite membranes were studied by FT-IR, , differential scanning calorimetry (DSC) and thermal stability. The proton conductivity as a function of temperature decreased as content increased, but methanol permeability decreased. The nano composite membranes were found to posse all requisite properties; Ion exchange capacity (1.2meq./g), glass transition temperatures , and low affinity towards methanol .