A fixed bed reactor is used to study the catalytic oxidation of carbon monoxide (CO) using activated carbon impregnated with poly-metals (copper, chromium and silver) as the catalyst. The conversion factor of carbon monoxide was measured under different operation conditions such as reactor bed height, catalyst particle diameter, and temperature. The conditions for which the mass transfer resistance could be eliminated are studied. With such conditions satisfied the surface reaction on the catalyst will be the rate controlling step, and the oxidation of CO was found to follow a first-order catalytic reaction. The reaction activation energy of CO in the copper impregnated carbon bed is found to be 107.2 kJ/ml. (C) 2003 Elsevier B.V. All rights reserved.