A new Aquivion (TM) E79-03S short-side chain perfluorosulfonic membrane with a thickness of 30 mu m (dry form) and an equivalent weight (EW) of 790 g/equiv recently developed by Solvay-Solexis for high-temperature operation was tested in a pressurised (3 bar abs.) polymer electrolyte membrane (PEM) single cell at a temperature of 130 degrees C. For comparison, a standard Nafion (TM) membrane (EW 1100 g/equiv) of similar thickness (50 mu m) was investigated under similar operating conditions. Both membranes were tested for high temperature operation in conjunction with an in-house prepared carbon supported Pt electrocatalyst. The electrocatalyst consisted of nanosized Pt particles (particle size similar to 2 nm) dispersed on a high surface area carbon black. The electrochemical tests showed better performance for the Aquivion (TM) membrane as compared to Nafion (TM) with promising properties for high temperature PEM fuel cell applications. Beside the higher open circuit voltage and lower ohmic constraints, a higher electrocatalytic activity was observed at high temperature for the electrocatalyst-Aquivion (TM) ionomer interface indicating a better catalyst utilization. (C) 2011 Elsevier B.V. All rights reserved.