The effect of adding hydrogen peroxide on a methanol-based chlorine dioxide generation process was studied. We found that the rate of chlorine dioxide generation is increased and that chlorine, usually present as a byproduct in the chlorine dioxide solution, can be largely eliminated when hydrogen peroxide is present as a coreducing agent. A possible explanation to account for these observations was given. An implication of these experimental findings for the operation of commercial chlorine dioxide generators was suggested.