Effects of supports such as silica, gamma-alumina, and zirconia for nickel catalysts have been studied in steam reforming of methane at 500degreesC. The activity of nickel supported on silica reduced with hydrogen at 500degreesC decreases with oxidation of nickel particles by steam during the reaction. Nickel supported on gamma-alumina is not much reduced with hydrogen at 500degreesC and is inactive in the reforming at 500degreesC. However, the catalyst reduced at 700degreesC is fairly active while nickel is partially oxidized during the reaction. Nickel supported on zirconia is the most effective in the stream reforming at 500degreesC. In the initial stage of the reaction solely with methane at 500degreesC, surface hydroxyl groups on these catalysts react readily with methane to produce hydrogen and carbon dioxide; suggesting that the hydroxyl groups play an important role in the mechanism of the steam reforming to carbon dioxide. A significant quantity of water can be accumulated on the surface of zirconia-supported nickel in the reaction only with steam at 500degreesC, and this results in formation of significant quantities of hydrogen and carbon dioxide in the following reaction with methane. (C) 2003 Elsevier B.V. All rights reserved.