The positively charged ions of palladium particles are obtained by reducing the solution containing metallic ions in the presence of PDDA (poly-diallyldimethylammonium chloride) medium. The nascent palladium particles are dispersed evenly on the surface of the perfluorosulfonate proton-conducting electrolyte membrane and bonded firmly to the activation center of the membrane. The mechanical strength of membrane is greatly enhanced by surface modi. cation. And the methanol diffusion coefficients of the modified membrane are decreased prominently by the deposition of palladium particles on the surface, which serves as a natural barrier for methanol crossing. (C) 2008 Elsevier B. V. All rights reserved.