Nickel catalysts supported on pure metal oxides (ZnO, MgO, ZrO2, TiO2, and Al2O3) with different acidity were prepared by an incipient wetness impregnation method, and they were applied to the hydrogen production by auto-thermal reforming of ethanol. The effect of support acidity on the catalytic performance of supported nickel catalysts was investigated. It was revealed that acidity of support played an important role in determining the reaction pathway and catalytic performance in the auto-thermal reforming of ethanol. Among various pure metal oxides, ZrO2 and TiO2 with an intermediate acidity were found to be efficient supporting materials for nickel catalysts in the auto-thermal reforming of ethanol. On the basis of this result, a series of TiO2-ZrO2 mixed metal oxides (TixZr1-xO2) with different Ti content (X) were prepared by a sol-gel method for use as supporting materials for nickel catalysts. In hydrogen production by auto-thermal reforming of ethanol, an optimal Ti content was required for suitable acidity of TixZr1-xO2 support and favorable reducibility of Ni/TixZr1-xO2 catalyst. Hydrogen yield over nickel catalysts supported on metal oxides showed a volcano-shaped curve with respect to acidity of the support. Among the catalysts tested. Ni/Ti0.2Zr0.8O2 with an intermediate acidity of support exhibited the best catalytic performance. (C) 2010 Elsevier B.V. All rights reserved.