The degradation of aqueous chlorinated compounds such as trichloroethylene (TCE), tetrachloroethylene (PCE) and dichloroacetic acid (DCA) to CO₂ and HCI was accomplished in the presence of UV light and suspended TiO₂ slurries. The decomposition of chlorinated hydrocarbons at 253.7 ㎚ irradiation was more effective than that at 360 ㎚ irradiation. Our results show that 253.7 ㎚ irradiation alone can be used for decomposing some chlorinated hydrocarbons such as PCE and TCE.