Most of studies for on-board hydrogen production for fuel cells are based on two types of carbon compounds. One is oxygen-containing compounds, methanol, ethanol and etc. The others are hydrocarbons such as ethers (dimethylether, etc), natural gas, propane gas, gasoline, jet fuel and diesel fuel. Automotive Polymer Electrolyte Membrane Fuel Cell (PEMFC) requires hydrogen gas to operate. The most convenient way to obtain the gas would be to use an on-board fuel processor to convert or reform commonly available liquid fuels, such as gasoline, methanol, and ethanol, into hydrogen. In this study, Methanol is used as hydrogen source which is also convenient for production, transportation and storage. PEMFC with methanol fuel process system, which is mainly composed of two parts, methanol reforming reaction and preferential oxidation (PROX), has been evaluated to study the enhancing stability of the system.