The crosslinked polybenzimidazole (PBI) proton exchange membrane is prepared by blending the epoxy (diglycidyl ether bisphenol-A) resin in the PBI with an imidazole-NH/epoxide Eqv. no. ratio ranging from 20/1 to 6/1. We show that the mechanical properties of the PBI membrane are improved by introducing a small quantity of crosslinks in the membranes (i.e., an imidazole-NH/epoxide Eqv. no. ratio of 15/1-10/1). Due to its high mechanical strength, the thinner crosslinked PBI membrane (thickness similar to 50 mu m) has a similar H-2/O-2 gas barrier property to the thicker PBI membrane (thickness similar to 80 mu m). Thus, the proton transport resistance across the membrane thickness direction of the thinner crosslinked PBI membrane is lower than that of the thicker non-crosslinked PBI membrane. We show that the crosslinked PBI membrane has a better fuel cell performance than the non-crosslinked PBI membrane at 160 degrees C with a non-humidified H-2 gas. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.