Butane was investigated as a fuel for a portable generator using the polymer electrolyte fuel cell (PEFC). A steam reforming technology was applied and Ru was investigated as a catalyst for a reforming process and a selective oxidation process. It was found that Ru realized a high space velocity (SV) which enables to reduce a volume of the reformer. Reformer manufactured was connected with PEFC and operated using butane, indicating that a drop of the cell voltage was small enough. Concentration of CO in the reformate gas was less than 10ppm.