The Nafion/zeolite composite membranes were synthesized for polymer electrolyte fuel cells (PEMFCs) by adding zeolite in the matrix of Nafion polymer. Two kinds of zeolites, Analcime and Faujasite, having different Si/Al ratio were used. The physico-chemical properties of the composite membranes such as water uptake, ion-exchange capacity, hydrogen permeability, and proton conductivity were determined. The fabricated composite membranes showed the significant improvement of all tested properties compared to that of pure Nafion membrane. The maximum proton conductivity of 0.4373 S cm(-1) was obtained from Nafion/Analcime (15%) at 80 degrees C which was 6.8 times of pure Nafion (0.0642 S cm(-1) at 80 degrees C). Conclusively, Analcime exhibited higher improvement than Faujasite. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.