Trichloroethylene (TCE) has been widely used in industry. It is considered a hazardous and carcinogenic air pollutant. In this investigation, TCE photocatalytic reactions were performed in a packed bed reactor configured as a continuous flow reactor and a FT-IR sample cell used as a batch reactor to determine the intermediates under irradiation by 365 nm UV light. In this study, the intermediates detected during these reactions were phosgene, dichloroacetyl chloride (DCAC), chloroform, hexachloroethane, alcohols, esters, aldehydes, carbon monoxide, and carbon dioxide. The possible reaction mechanisms began with the Cl- subtraction. The Cl radicals then interacted with TCE to form various intermediates and products. (C) 2002 Elsevier Science B.V. All rights reserved.