IrO2, a water electrolysis catalyst, has been known to be effective in preventing corrosion of the carbon support in proton exchange membrane fuel cells (PEMFCs). Particulate IrO2 can agglomerate easily, which can decrease substantially the catalytic surface area required for oxygen evolution reaction, causing the loss of catalytic efficiency. Furthermore, agglomerated IrO2 nanoparticles can have an adverse effect on the oxygen reduction reaction by covering the active surface area of the Pt/C cathode catalyst, which is a damaging factor for the intrinsic performance of PEMFC. Carbon-supported iridium oxide, IrO2/C, which can prevent the agglomeration of Ir nanoparticles more effectively, was synthesized to overcome these problems. Compared to the cell with the Pt/C cathode only, the cell with 10 wt.% IrO2 particles and Pt/C cathode showed stronger durability during fuel starvation but the cell performance at normal operation decreased severely by 35%. The cell with the same amount of IrO2 dispersed on a carbon support, 10 wt.% IrO2/C, showed similar durability during fuel starvation maintaining the cell performance comparable to the cell using a Pt/C cathode only. Carbon-supported IrO2, IrO2/C, was more effective than IrO2 particles in both maintaining the intrinsic performance and improving the cell durability during fuel starvation. (c) 2012 Elsevier Ltd. All rights reserved.