An organic solution of a soluble molybdenum compound is ammonated with ammonia, ammonium hydroxide and/or an ammonium salt in order to significantly reduce the electrical resistance of the solution and a direct electric current is passed therethrough in order to collect a significant amount of the molybdenum in solid form at the negative electrode. Preferably, an epoxidation reaction product formed by the molybdenum catalyzed reaction of propylene with tertiary butyl hydroperoxide to provide propylene oxide and tertiary butyl alcohol is separated by distillation into a propylene fraction, a propylene oxide fraction, a tertiary butyl alcohol fraction and a heavy liquid distillation fraction containing substantially all of the dissolved molybdenum catalyst, the heavy liquid distillation fraction is saturated with ammonia to precipitate the molybdenum therefrom, the precipitated molybdenum is removed from the ammonated heavy distillation fraction and a direct electric current is passed through the remaining liquid portion of the ammonated fraction in an electrolytic cell in order to collect a significant portion of the remaining molybdenum residually dissolved therein at the cathode.