Hydrogen peroxide (H2O2) is commonly produced by redox reactions involving organic compounds in organic medium, but such processes present several limitations including the need to extract and concentrate a highly active product. Hydrogen peroxide can be generated in situ by the electrochemical reduction of oxygen in aqueous medium, and the process is particularly efficient when gas diffusion electrodes (GDEs) are employed. A key challenge in the development of such electrodes is the choice of the catalytic particles. This paper describes the evaluation of iron (II) phthalocyanine as a modifier of pigment carbon black used in the construction of GDEs. After 90 min of electrolysis at constant potential, a GDE containing 5% of modifier generated 240 mg L-1 of H2O2 (rate constant 7 mg L-1 min(-1); energy consumption 165 kW h kg(-1) H2O2) while the unmodified GDE produced only 175 mg L-1 of H2O2 (3 mg L-1 min(-1); 300 kW h kg(-1) H2O2) under the same experimental conditions. (C) 2014 Elsevier B.V. All rights reserved.