It is demonstrated that hydrogen peroxide can be produced with a current efficiency of 40-70% by the reduction of oxygen at a reticulated vitreous carbon cathode in a divided flow cell using catholytes consisting of aqueous chloride or sulfate media, pH approximate to 2. The influence of ferrous salts, potential and electrolyte concentration on the current efficiency and rate of H2O2 production is reported; ferrous ions can lead to the homogeneous decomposition of H2O2 away from the cathode surface but their effectiveness as a catalyst for this decomposition depends on their speciation in solution which changes during an electrolysis. The conclusions are supported by voltammetry at both a rotating vitreous carbon disc and the reticulated vitreous carbon electrodes.