The start-up and shut-down procedures of an autothermal reformer were investigated to understand the issues affecting catalyst degradation. This investigation gives insight into the transient response using fuel-lean and fuel-rich start-up and shut-down methodologies. Sudden repeated temperature changes on the top surface of the catalyst caused by oxidation show a gradual loss of catalytic activity. A number of start-up and shut-down cycles were repeated for both fuel-lean and fuel-rich methodologies to and from a fixed steady state O-2/CH3OH ratio. The experimental results gathered can provide insight in order to develop adequate start-up and shut-down procedures using autothermal reformation. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.