This work investigated several basic parameters, important for extending photocatalytic purification of water contaminated with trichloroethylene (TCE), from the laboratory to the field. Some of these variables strongly influence the decomposition kinetics of the TCE. Parameters investigated were the effect of solution pH, initial TCE concentration, presence of naturally occurring ions, temperature and presence of 'color bodies.' It was found that the photocatalytic decomposition of aqueous TCE occurs more than twice as fast in the pH range 6.4 to 9 than in the range 3.4 to 5. Additionally, various photocatalyst materials were also tested but titanium dioxide exhibited superior activity in decomposing TCE. In this laboratory study low intensity irradiation having the equivalent intensity of 1/4 to 1/5 Solar at AM1 was employed in order to exemplify the feasibility of large scale water purification utilizing natural solar light.