This paper summarizes a study of combining ultra-violet radiation and ozone to purify water contaminated with microorganisms and organic compounds.The objectives of the study were (1) to determine the feasibility of the combination of ultraviolet light and ozone to sterilize and to remove organics from water, (2) define the concentrations of ultraviolet light and ozone required to remove predetermined levels of microbial contamination and organic substances from water, and (3) to describe operating parameters for water sterilization and purification that can be used as a basis for designing operating systems that can be used by the Army and in manned space flight.The study to date has found that the combination of UV and ozone is more effective in destroying test organisms than UV alone. About 2.25 ppm ozone plus UV will destroy about 99.7 percent of the organisms present and 3 ppm of ozone plus UV will result in complete destruction of the organisms.The process was found to partially oxidize 10 mg/l hydroquinone, xylenol and pyrogallol in water. The best result to date was the 94% oxidation of xylenol using 0.17 mg/l O3 in air at a flow rate of 7.5 l/min. over a one hour period. Work is continuing to define the most economical operating conditions needed to obtain maximum oxidation of the test organics.