The H-2 and H2O2 produced by Co-60 gamma-radiation at room temperature were measured in pure water and 0.4 M H2SO4 aqueous solution with alumina powder. By increasing the addition of alumina powder, a strong reduction of H2O2 concentrations in the solutions was obtained, and the final product H-2 yields were correspondingly enhanced. These enhancement and reduction effects were diminished in the subsequent gamma-radiation when irradiated alumina powder was used. The effects were reversibly restored by washing the irradiated powder with purified water. In 0.4 M H2SO4 solution with alumina powder, the H2 yields increased by increasing the absorbed dose rate in the region of 1-5 kGy/h. The radiation-enhanced H-2 production correlated with the reduction of H2O2 concentration could be brought about by the reduction of H2O2 molecules and OH radicals in the solutions due to alumina powder. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.