The effect of adding air to the feed in methane steam reforming over Ni/gamma-AL(2)O(3) was investigated. The catalyst exhibited a high specific surface area, but low metal surface area, with large Ni particles, which favor the deposition of carbon. A great quantity of carbon was seen to form on the catalyst during steam reforming, without any decrease in the reaction rate. This constant catalytic activity was consistent with the formation of filamentous whiskers of carbon during the process, verified by scanning electron microscopy. The addition of air decreased the energy consumed by the reaction and reduced significantly the carbon deposited on the catalyst during the process, making it a viable alternative for industrial application. (C) 2004 Elsevier B.V. All rights reserved.