Hydrated nanoporous controlled pore glasses have been irradiated with gamma-rays or 10 MeV electrons and the formation of hydrogen peroxide (H2O2) upon irradiation has been quantified. Under gamma-irradiation the H2O2 formation is strongly enhanced as compared to bulk water, evidencing an efficient energy transfer from silica to confined water. In the case of high dose rate irradiations using 10 MeV electrons, the H2O2 radiolytic yields are much smaller and comparable to the value obtained in bulk water: no energy transfer is any more possible. In all cases, H2O2 is the oxidant counterpart to H-2 in the radiolysis of hydrated glasses. (C) 2007 Elsevier B.V. All rights reserved.