An Ir0.7Ru0.3Ox nanosized anode electrocatalyst was coupled to an Aquivion short-side chain perfluoro-sulfonic acid membrane (120 mu m; EW: 870 g/eq) for operation in a PEM electrolyser. A conventional carbon supported Pt catalyst was used as cathode. An excellent performance, of 4 A cm(-2) at 1.9 V at 90 degrees C, was achieved for this electrolyser configuration in the presence of a moderate noble metal loading (1.5 mg cm(-2) Ir + Ru; 0.5 mg cm(-2) Pt). The interface of IrRuOx with Aquivion provided a 10% enhancement in performance compared to an equivalent interface with a Nafion membrane of similar thickness but characterized by a larger equivalent weight (EW: 1100 g/eq). The enhanced performance essentially derived from a decrease of polarization resistance. This appeared to be due to better interface characteristics between the electrodes and Aquivion (R) ionomer giving rise to an increased catalyst utilization. Whereas, no significant change in Tafel slope and activation energy was recorded indicating a similar reaction mechanism. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.