Development of catalysts for steam reforming of dimethyl ether (DME) producing hydrogen was carried out with the aim of improving catalyst durability. The catalyst consisted of a mixture of solid acid catalysts for hydration of DME to methanol and 40 wt.% CuO/CeO2 catalyst for steam reforming of methanol. Among various acid catalysts examined, 10 Wt-% WO3/ZrO2 had the highest performance. WO3/ZrO2 showed a unique feature that the activity and durability of the combined Catalysis (WO3/ZrO2 + 40 wt.% CUO/CCO2) significantly changed depending upon the amounts Of WO3 loaded on ZrO2 and the calcination temperatures of WO3/ZrO2. WO3/ZrO, with low WOP3 loading (5 Wt.% WO3) combined with 40 wt.% CuO/CeO2 had only low activity and those with high loadings (more than 15 Wt-% WO3) and calcined at 700 'C had high activity but they were deactivated in a few hours. Calcination at 800 'C prevented deactivation of the catalyst even with high W-loadings. Since hydration of DME proceeded even after deactivation, WO3/ZrO2 was not deactivated but deactivation occurred oil the CuO/CeO2 side. It was deduced that WO3/ZrO2 caused the deactivation of CuO/CeO2: TPO measurements of the used catalysts showed that carbonaceous precursors formed on WO3/ZrO2 were transferred to CuO/CeO2 and deposited as coke. Characterization Of WO3/ZrO2 by BET, XRD and XPS measurements suggested that WO3 formed a monolayer on ZrO2 UP to WOP3 loading of 12-13 wt.%. The excess WO3 Over monolayer loading formed carbonaccous precursors during the reaction and caused the deactivation of CuO/CeO2. The excess surface WO3 was not bound directly to ZrO2 and was fragile against heat. Therefore, it changed into bulk WO3 during high temperature calcination and lost its function to form carbonaceous precursors. Durability of the optimized catalyst consisting of 80 Wt.% CUO/CeO2 and 10 Wt.% WO3/ZrO, calcined at 800 degrees C was examined during 100 h reaction at 250 degrees C. This catalyst maintained high activity and no fatal deactivation occured. The used catalyst could be regenerated by treatment with oxygen at 300 degrees C. (c) 2005 Elsevier B.V. All rights reserved.