Effective catalytic water-splitting can be electrochemically triggered in an alkaline solution of sodium hypochlorite. Hypochlorite oxidation on polycrystalline platinum yields CIO center dot radicals, which initiate a radical-assisted water-splitting, yielding oxygen, hydrogen peroxide, and protons. The efficiency of the O-2 production corresponds to about two elect-tons per molecule of the produced O-2 and is controlled primarily by the hypochlorite concentration and pH.