Abstract: Sodium hypochlorite is a strong oxidation agent，while it usually decomposes into hydrogen chloride under natural conditions. Ni2O3 catalyst prepared by a mixing method can make sodium hypochlorite decompose to atomic oxygen. Such atomic oxygen produced is very active，hence the oxidation ability of sodium hypochlorite could be greatly enhanced. The physicochemical properties and catalytic performance of the catalyst were investigated by X-ray diffraction (XRD)，scanning electron microscope (SEM) and BET. The decomposition rate of sodium hypochlorite yielding atomic oxygen was evaluated with the catalyst in different proportion，concentration，pH，and temperatures. The decomposition rate increases with increasing sodium hypochlorite concentration，and a neutral or weak acid environment as well as a higher temperature is favorable for the reaction. Preliminary experiment for organic waste water treatment illustrated that the COD removal efficiency for methanol，toluene and metanilic acid was 91.3%，89.28% and 84.53%，respectively.