The reaction of steam reforming of ethanol over nickel catalysts supported on gamma-Al2O3, La2O3, and La2O3/gamma-Al2O3 is investigated employing transient and steady-state techniques. It is found that ethanol interacts strongly with alumina on the surface of which it is dehydrated at low temperatures. and less strongly with lanthana on the surface of which it is both dehydrogenated and dehydrated. Cracking reactions are also observed on the carriers at intermediate temperatures. In the presence of Ni, catalytic activity is shifted toward lower temperatures. In addition to the above reactions, reforming, water-gas shift, and methanation contribute significantly to product distribution. Carbon deposition is also a significant route. It is found that the rate of carbon deposition is a strong function of the carrier, the steam-to-ethanol ratio, and reaction temperature. The presence of lanthana on the catalyst, high steam-to-ethanol ratio, and high temperature offer enhanced resistance toward carbon deposition. (C) 2004 Elsevier Inc. All rights reserved.