The stability and activity of 10 mol % mobium-doped titania (10Nb-TiO2) were compared to those of commercial Pt/C catalyst (HiSpec 4000), both ex situ and in a proton exchange membrane fuel cell. The stability test involved holding the cell at 1.4 V for 20 h. Fuel cell polarization curves were obtained both before and after the potential holds. Cyclic voltammogram data showed that the Pt surface area was stable for Pt/10Nb-TiO2 even after holding for 60 h at 1.4 V. A significant drop in the Pt surface area was observed, however, for Pt/C after 20 h at 1.4 V. The high potential hold test showed significantly higher stability of the membrane electrode assembly with Pt/10Nb-TiO2 compared to that with Pt/C. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3184155] All rights reserved.