These reactions occur with high yield and satisfactory rate only at three-dimensional carbon-based cathodes (Alvarez Gallegos and Pletcher, 1998; Sudoh et al., 2001; Yamada et al., 2001; Qiang et al., 2002; Da Pozzo et al., 2005a), due to the low solubility of oxygen in aqueous solutions. More recently, gasdiffusion cathodes (GDE) have demonstrated to be promising electrode materials for the electrogeneration of H2O2 from oxygen reduction