Poly( 1,4-phenylene sulfide) was sulfonated with chlorosulfonic acid in 1,2-dichloroethane. The product (IEC = 2.38 mequiv./g) was ground and sieved (mesh size 63 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 in mechanical strength. The membranes were characterized by their stability in oxidative environment, ionic conductivity, and diffusive permeability to methanol. The membrane containing 66 wt.% of sulfonated particles was almost as conductive as Nafion 117; it exhibited, however, much lower diffusive permeability to methanol. In a strongly oxidative environment (3% aqueous H2O2 at 70 degrees C), the prepared membranes were less stable than Nafion 117, but much more stable than membranes with sulfonated poly (styrene-co-divinylbenzene) particles. In preliminary laboratory tests with H-2/O-2 and direct methanol fuel cells, the prepared membranes with high concentrations of sulfonated particles performed similarly to Nation 117. (c) 2004 Elsevier B.V. All rights reserved.