Several radiation grafted ion exchange membranes were prepared and evaluated in half-cells and direct borohydride fuel cells (DBFC) using voltammetric and steady-state polarisation techniques. The peak power density of 112 mW cm(-2) was achieved in a DBFC with an ETFE-g-PSSA membrane using a solution of 1.32 M sodium borohydride and 2.5 M sodium hydroxide, 1 bar oxygen at 85 degrees C. The chemical and mechanical stabilities of the membranes were tested under various conditions. The membrane performance was compared to that obtained with the benchmark Nafion((R)) 117 membrane. The results are discussed based on the electrical, chemical, structural and mechanical properties of the membranes. (c) 2006 Elsevier B.V. All rights reserved.