One-dimensional manganese oxide (MnO2) scavengers are proposed to minimize the radical degradation of membrane electrode assembly (MEA) in fuel cells. The synthesized MnO2 nanotubes and MnO2 nanowires are ca. 5-8 nm in diameter and more than 100 nm in length, respectively. Water retention of the hydrophilic MnO2 reduces the humidity sensitivity of the fuel cells. At 75 RH% humidify levels of inlet gas at 60 degrees C, single cells assembled by catalyst layer with MnO2 nanotubes and nanowires as the cathodes have peak power densities of 599.3 and 536.8 mW cm(-2), respectively. Radical scavenger MnO2 in the cathode catalyst is effective in minimizing the radical degradation in proton exchange membrane (PEM) fuel cells. After the OCV degradation, the hydrogen crossover of cell assembled by catalyst layer with MnO2 nanowires or MnO2 nanotubes in anode and traditional catalyst layer in cathode are about 5.3 and 4.9 mA cm(-2), respectively. As a comparison, single cell with conventional catalyst layer in both anode and cathode, the hydrogen crossover through the MEA is increased to 14.7 mA cm(-2). (C) 2012 Elsevier B.V. All rights reserved.