Poly(1,4-phenylene sulfide) was sulfonated with fuming sulfuric acid to different degrees. The products were ground and sieved (mesh size 50 mu m) to obtain small particles. The particles and linear polyethylene were mixed in various ratios and the resulting blends were press-molded at 150 degrees C to obtain the membranes. Membranes containing up to 66 wt.% of sulfonated particles could be prepared without any problem with the required mechanical strength. The membranes with high concentrations of highly sulfonated particles were as conductive as Nafion 117 membranes and had high values of permselectivity in HCl solutions.