Advanced life support research at NASA Johnson Space Center is focused on developing regenerative life support systems to support longer duration missions. One component of human life support, trace contaminant control, presently relies on non regenerative charcoal adsorption. Photocatalytic oxidation holds great promise as a regenerative alternative to charcoal adsorption. It operates at ambient temperature, oxidizes a wide variety of organics, and has rapid destruction kinetics at low concentrations. While the scientific concept of photocatalysis has been demonstrated, many of the engineering issues associated with photocatalytic oxidation have not yet been adequately addressed. The effects of dewpoint, catalyst poisoning and rejuvenation, complex contaminant streams, and reactor design are some of the issues that must be better understood before this technology can be turned into flight hardware. This paper briefly describes photocatalytic processes, and relates photocatalysis to spacecraft life support systems.