Our previous work confirmed the excellent activity of CuO-MoO3/Al2O3 for the destructive oxidation of (CH3)(2)S-2. This study further investigates the effect of acid treatment on the performance of this catalyst. Four different kinds of inorganic acids (HCl, H2SO4, HNO3, H3PO4) are used to treat the gamma-Al2O3 support before impregnating it with copper and molybdenum metal salts. The prepared catalysts are then used for the destructive oxidation of (CH3)(2)S-2. Experimental results indicate that HCl-treated and H2SO4-treated catalysts exhibit a higher activity than those without acid treatment. In addition, the H2SO4-treated catalyst (CuO-MoO3/Al2O3-SO42-) displays the best stability. As BET surface area analysis demonstrates, the surface area and average pore diameter of the H2SO4-treated catalysts are larger than those without treatment; however, the increase in surface area is not the main factor in promoting the activity. XRD analysis reveals that the CuO-MoO3/Al2O3-SO42- catalyst also has the crystalline structure of Cu3Mo2O9 and CuMoO4 which have been found in CuO-MoO3/Al2O3 and which might play a prominent role in the catalyst activity. XPS and TGA analyses suggest that it might have the functional group of SO42- which exists on the surface of the CuO-MoO3/Al2O3-SO42- catalyst. The NH3-TPD pattern shows that the acidity is remarkably enhanced when the catalyst is treated with an H2SO4 solution. We believe that the substantial increase in activity is attributed primarily to the presence of the SO42- group and the formation of a copper molybdenum oxide phase on the catalyst surface.