Samples of mesoporous gamma-aluminas were synthesized by a post-hydrolysis method which contained different mole ratios of stearic acid (surfactant)/Al(sec-OBu)(3) (aluminum precursor). The Ni catalysts supported on aluminas were then prepared by an impregnation method used as catalysts in the hydrodechlorination of 1,2-dichloropropane. The effect of the mole ratio of surfactant/aluminum precursor on the properties of aluminas and supported Ni catalysts was investigated. The dissolution of aluminum occurred during the impregnation step, and the amounts of aluminum dissolved were correlated with the mole ratio of surfactant/aluminum precursor. As the mole ratio of surfactant/aluminum precursor increased, large amounts of aluminum ions were dissolved in the nickel nitrate solution, leading to the formation of large amounts of nickel aluminate species in the supported catalyst. A supported catalyst that contained a large portion of nickel aluminate species was resistant to being reduced to active nickel metal efficient for the hydrodechlorination. When the nickel was impregnated on an alumina, which was prepared with low mole ratio of surfactant/aluminum precursor, the supported catalyst exhibited the enhanced catalytic activity in the hydrodechlorination of 1,2-dichloropropane. (C) 2004 Elsevier B.V. All rights reserved.