A novel phosphoric acid doped Nation-polybenzimidazole (H3PO4/Nafion-PBl) composite membrane was prepared and the H-2/O-2 single cell durability was tested at 150 degrees C without humidification. The durability was improved 55% compared with that of phosphoric acid doped polybenzimidazole (H3PO4/PBI). During the durability test, the hydrogen permeability of the membrane and the internal resistance of the single cell were detected using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS), respectively. Before and after the durability test, the mechanical strength of the membranes was measured by stress-strain tests. The results of characterization indicated that the enhanced durability of the membrane attributed to the improved mechanical strength, which benefited from the presence of Nafion in the Nation and PBI matrix. The preliminary results suggested that the novel H3PO4/Nafion-PBI composite membrane is a good candidate in high temperature PEMFC for achieving longer cell lifetime. (c) 2007 Elsevier B.V All rights reserved.