Photocatalytic degradation of trichloroethylene (TCE) over Pt/Pd-doped TiO2 was conducted to investigate the effect of Pt and Pd on the TCE degradation and on the yields of dichloroacetyl chloride (DCAC) and phosgene. In the presence of Pt and Pd, the degradation of TCE was retarded; especially Pd had a significantly negative effect on TCE degradation, which was ascribed to the intercalation of Pd into the lattice of TiO2. Moreover, Pt had no influence on the selectivity toward DCAC and phosgene while the selectivity toward phosgene in the presence of Pd was enhanced. As for the behavior of Pt and Pd in TCE degradation, Pt-doped TiO2 exhibited the same photocatalytic behavior as P25 TiO2 whereas Pd-doped TiO2 led to a different photocatalytic mechanism. (c) 2007 Elsevier B.V. All rights reserved.