A novel Pt/zeolite-Nafion (PZN) polymer electrolyte composite membrane is fabricated for self-humidifying polymer electrolyte membrane fuel cells (PEMFCs). A uniform dispersion of Pt nanoparticles with an average size of 3 mn is achieved by ion-exchange of the zeolite HY The Pt nanoparticles embedded in the membrane provide the catalytic sites for water generation, whereas the zeolite HY-supported Pt particles absorbs water and make it available for humidification during cell operation at elevated temperature. Compared with the performance of ordinary membranes, the performance of cells with PZN membranes is improved significantly under dry conditions. With dry H-2 and O-2 at 50 degrees C, the PZN membrane with 0.65 wt.% of Pt/zeolite (0.03 mg Pt cm(-2)) gives 75% of the performance obtained at 0.6 V with the humidified reactants at 75 degrees C. Impedance analysis reveales that an increase in charge-transfer resistance is mainly responsible for the cell performance loss operated with dry gases. (c) 2006 Elsevier B.V. All rights reserved.