The effect of flue gas components on the Hg-0 oxidation efficiency of CuO/TiO2 and CuCl2/TiO2 catalysts was investigated. The results indicated that HCl and O-2 in the atmosphere positively affect Hg-0 oxidation, and HCl is more effective than O-2. Meanwhile, atomic Cl and O in the catalyst also play crucial roles in the Hg-0 oxidation process. Thermogravimetry (TG), X-ray Diffractograms (XRD), Brunauer-Emmet-Teller (BET) and X-ray photoelectron spectroscopy (XPS) technologies were adopted to characterize the raw CuCl2/Tio(2) catalyst. The Hg-0 oxidation mechanisms over CuO/TiO2 and CuCl2/TiO2 catalysts were discussed. Both HCl and O-2 gases were found to be necessary to revert to CuO or CuCl2 via an intermediate step. The CuCl2/TiO2 catalyst has a potential industrial application because it has a certain oxidation activity in the absence of HCl, high stability and a large temperature window. (C) 2014 Elsevier B.V. All rights reserved.