In this research a series of pore-filling electrolyte membranes were prepared, based on a sulfonated and hydrogenated styrene/butadiene block copolymer (SHSBS) and plasma-treated microporous polyethylene (PE) membranes. The pore-filling electrolyte membranes were characterized by means of scanning electronic microscopy (SEM), infrared spectroscopy (FTIR-ATR), and dynamic mechanical analysis (DMA). In addition, the water uptake and methanol/water uptake capacities of these membranes were determined using several methanol in water solutions, as well as the permeability coefficients, for both water and methanol, using a 2 M methanol in water solution and pure methanol. Finally, electrical behavior was recorded by means of electrochemical impedance spectroscopy (EIS) and the four probe technique (FPT). The SEM images recorded show good coating of the pore-filling electrolyte membranes on the plasma-treated PE matrices, and DMA shows the proper relaxations of the two components: PE and SHSBS. Furthermore, the methanol/water absorption capacity was observed to diminish with plasma treatment of the matrix. Methanol permeability of the pore-filling electrolyte membranes is notably lower than that of the Nafion membrane, ion conductivity moving in the order of 10(-2) S cm(-1). Both of these characteristics qualify the experimental membranes as candidates to be applied as proton exchangers in fuel cells (FCs). (C) 2008 Wiley Periodicals, Inc.