Selection of the optimum catalyst for the reformation of methanol, and static/dynamic characteristics of a spark ignition engine fueld with both gasoline and methanol reformed gas were studied. Tube test results on reforming characteristics show that a catalyst made of a base metal works best. A methanol reformer with an exhaust gas heat exchanger was used. Results show that the increase of reformed gas ratio increases the stability of combustion and extends the lean limit. It also improves thermal efficiency, owing to the reduced duration of combustion. Moreover, responses of Pmax during sudden opening/closing of the throttle valve were studied. Results indicate that the higher the reformed gas ratio, the quicker the Pmax response and the smoother the combustion process.