Abstract: An improved catalytic process for the ozonation of water containing organic contaminants is disclosed. In this process the water, which may be either waste water or potable water, containing organic contaminants is contacted with ozone, preferably at a pH in the range of about 6.8 to about 7.8 (controlled by buffering if necessary), in the presence of a mixed heterogeneous catalyst comprising water insoluble salts, preferably an insoluble carbonate, sulfate, oxide, halide or sulfide, of at least two metals selected from the group consisting of copper, cadmium and the group VIII metals, preferably iron, cobalt or nickel although other group VIII metals such as platinum or Palladium may be used if desired.