In this research a miniaturized packed bed reactor is designed and analyzed, in which autothermal reforming of methanol occurs to produce sufficient hydrogen for generating 50 W of power. Mass and energy balance equations are developed for each species in the reactor. The pressure drop is modeled via the Ergun equation. Simulations are conducted in MATLAB to determine the effect of process parameters (e.g. steam to methanol ratio, oxygen to methanol ratio, inlet pressure, inlet temperature) on the production of hydrogen. For a range of catalyst particle sizes considered, it is shown that the pressure drop is negligible. An appropriate reactor jacket is designed where methanol is oxidized to produce sufficient heat for the steam reforming reactions in the reactor. The flow rate of methanol in the jacket is computed so that sufficient heat is generated for complete conversion of methanol under non-isothermal conditions. Calculations are done for the energy required to bring the fuel processor system from ambient temperature to the operating temperature where fuel cell quality hydrogen can be produced. Effectiveness factor calculations are performed on a range of catalyst particle sizes. Finally, the simulation results are compared with experimental results from the literature.