A process for operating a methanol reforming system in which, in the reforming reaction operation, methanol is reformed in a methanol reforming reactor using a methanol reforming catalyst. The reforming reaction operation is interrupted periodically for catalyst reactivation phases during which the methanol reforming catalyst whose catalytic activity decreases in the reforming reaction operation is treated in an activity-regenerating manner. The process may be used in fuel-cell-driven motor vehicles for generating hydrogen for the fuel cells from methanol carried along in the liquid state.