A study was made to determine the optimum conditions for precipitation of uranium from mill solutions usxdg hydrogen peroxide. Precipitation tests were made on both synthetic and actual mill solutions. Parameters studied included the amount hydrogen peroxide, initial ph, reaction ph, time, and temperature. Also investigated was the effect of varied amounts of vanadium, molybdenum, and sulfate in the test solution on uranium precipitation and product quality. The optimum conditions for complete precipitation and high product quality were (1) the use of 150 percent of the stoichiometric requirement of hydrogen peroxide, (2) initial ph of 1.0, (3) Reaction ph between 3.4 and 5.0, (4) 4 Hours reaction time, and (5) ambient reaction temperature. The excess hydrogen peroxide requirement is partially dependent on the amount of impurities present in the feed solution. The hydrogen peroxide process appeared applicable to treatment of the several mill eluate and strip solutions tested. The experimental studies also indicated that the hydrogen peroxide technique gives substantially better product quality than that produced by ammonia precipitation.