This paper consists of two parts. First, a complete thermodynamic analysis of autothermal methanol reforming over a wide range of air-fuel and water-fuel ratios is described. Second, a detailed description is given to the development of a ID, non-steady, oxidative methanol reformer model. Calculations of the chemical equilibrium composition show that the predicted H-2 yield in the fuel-water-air reaction system is always lower than that obtained from experiment, while the predicted CO is always higher than that obtained from experiment. Corrections are made to the predicted results by incorporating a water-gas shift reaction, whereby the CO is oxidized by water to produce more H. With this correction, the predicted H-2 and CO yields are in good agreement with the experimental results. Some preliminary results from the kinetic model are also presented. The model considers the heat/mass transfer phenomena associated with the kinetics of the methanol reaction, and is able to express the temporal and spatial variations of the temperature of the catalyst, the concentration of the reactant gases, and the conversion efficiency of methanol in the reformer. (C) 2003 Elsevier B.V. All rights reserved.