Sulfonated block copolymer was synthesized to prepare lower cost membranes having low methanol permeability as well as other desired performance such as high proton conductivity and chemical and thermal stability for the application of fuel cell electrolyte membrane and gas separation membranes. High sulfonation degree leads to high proton conductivity with low mechanical stability due to the swelling of membranes in water medium. To improve the proton conductivity without the loss of mechanical strength, various kinds of clays were empolyed into the sulfonated block copolymer membranes and examined their effects on membrane performance.