Steam reforming of dimethyl ether (DME) was carried out over WO3/ZrO2-CuO/CeO2 catalysts. The effect of the method of preparation of WO3/ZrO2 on its activity was investigated. Three kinds of WO3/ZrO2 were prepared by impregnating ammonium paratungstate (APT), ammonium metatungstate (AMT), and tungsten hexachloride (WCl). Although these WO3/ZrO2 catalysts had different activities, no difference was observed in their acidic property. The TG-DTA analysis clarified that the different kinds of W precursors affected the crystallization process of zirconia differently. The interaction with zirconia during calcination gave specific properties to the surface W species that are different from those of the single component WO3. The XPS study on the surface W species showed that H-2 production rate depended on the surface WO3 amount and on the W(V)/[W(VI) + W(V)] ratio. Excess WO3 loading brought about the decrease in H-2 production due to the formation of inactive bulk WO3. The active surface tungsten species were originated from W(V) components interacting with ZrO2. The APT gave the highest W(V)/[W(VI) + W(V)] ratio and, thus, was the best W precursor among the three. (C) 2006 Published by Elsevier B.V.