Alumina-supported Ni and/or Ru catalysts were prepared and their ability to decompose ammonia in simulated coal-derived gas fuel from 250 to 900 degrees C using a conventional fixed-bed flow reactor at atmospheric and high pressure (0.9MPa) was tested. The surface properties of the catalysts were investigated using BET, CO chemisorption, XRD, and TPD after NH3 adsorption. Supported Ni catalyst promoted NH3 decomposition to N-2 above 700 degrees C with and without oxygen addition in the fuel. Supported Ni catalyst had the potential to decompose NH3 to N-2 from 400 to 550 degrees C with the addition of a small amount of oxygen in the fuel, while the addition of Ru significantly reduced the potential. Ni selectively promotes NH3 oxidation to N-2 at low temperature, while Ru selectively promotes H-2 oxidation to H2O. (c) 2007 Elsevier Ltd. All rights reserved.