A novel thin three-layer reinforced and self-humidifying composite membrane has been developed for PEMFCs. The membrane has two outer layers of plain Nation and a middle layer of Pt/carbon nanotubes (Pt/CNTs) dispersed Nation. The Pt/CNTs present in the membrane provides the sites for the catalytic recombination of H-2 and O-2 permeating through the membrane from the anode and cathode to produce water and improve the mechanical properties of the composite membrane at the same time. The water produced directly humidifies the membrane and allows the operation of PEMFCs with dry reactants. The electrochemical performance and mechanical properties of the composite membranes are compared with those of a commercial Nafion((R)) membrane. The self-humidifying composite membrane could minimize membrane conductivity loss under dry conditions and improve mechanical strength due to the presence of the Pt/CNTs. (c) 2006 Elsevier B.V. All rights reserved.