The oxygen reduction reaction has been studied on gas diffusion electrodes made with various activated carbon materials and on the edge/basal orientations of pyrolitic graphite. A MnO2 catalyst was loaded on all carbon surfaces. The MnO2 catalyst demonstrated significant catalytic activity for the oxygen reduction reaction. The specific catalytic activity was found to relate to the concentration of the edge orientation of carbon materials loaded with MnO2 catalyst. The higher the percentage of edge orientations, the higher the specific catalytic activity would be. MnO2 may not participate in the reduction of O-2, but catalyze the disproportionation of HO2-. (C) 2010 Elsevier B.V. All rights reserved.