Abstract A study was made of the United States Bureau of Mines electrooxidation process for the recovery of molybdenum from molybdenite. The investigation sought to determine the effect of solution parameters on by-product chlorate formation and the resulting loss in current efficiency. The minimization of the chlorate production during the electrolytic oxidation of molybdenite would contribute to making the process economically attractive. The study showed that chlorate production could be minimized during electrooxidation by operating at low temperatures, low pH's, a large excess of molybdenite and low current densities. Anodes having a high oxygen overvoltage were found to favorably reduce chlorate production. The rate of dissolution of molybdenite under these conditions was also investigated. It was determined that the generation of hypochlorite was the rate controlling step. The rate of dissolution of molybdenite was found to be zero order. The zero-order rate constant equalled the rate of production of hypochlorite divided by the hypochlorite/molybdenite stoichiometric ratio.