A study has been carried out to investigate the dynamic behaviour of water-gas shift assisted autothermal reforming (ATR-WGS) utilising a 2-D heterogeneous kinetic model. The purpose of this study is to gain insights to the dynamic changes of ATR-WGS during cold start and when subjected to a sudden change in square-pulse flow rate. In addition to analysis of ATR-WGS, the model can also aid in guiding the design of a feedback controller aimed at improving the dynamic response of the system. Cold start time for ATR-WGS reactor was found to be longer than autothermal reforming (ATR) reactor due to the addition of a slower water-gas shift (WGS) process. It was also observed that WGS plays an important role in the final products of the reaction. In addition to these findings, the investigations in the transient performance of ATR-WGS showed that there are serious overshoot/undershoot of performance related parameters in the transients, whose values are quite different from those under steady state conditions. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.