The anodic decomposition of hydrogen peroxide has been investigated over a wide range of conditions. In alkaline, neutral, and acid solutions at all the anode materials investigated hydrogen peroxide is quantitatively decomposed, provided the current density is not too high, in accordance with the formal equation . In alkaline solution there appears to be a common process, occurring at a low potential, involving the ion, which can be simply formulated as ; this takes place rapidly and, in general, the rate of the total anode reaction is governed by diffusion. In neutral and acid solutions this process does not take place at appreciable speed, but there appears to be a common process, occurring at a high potential, which can be formulated as an interaction of the radical with the molecule. Platinum anodes in neutral and acid solutions show a specific behavior which is attributed to chemical interaction of hydrogen peroxide with platinous oxide, which is primarily formed on the anode surface.