The Japan Gas Association (JGA) has been executing technological programs under the subsidy of the New Energy and Industrial Technology Development Organization (NEDO) to market a polymer electrolyte fuel cell (PEFC) system developed with a view to putting a residential PEFC system into practice. The target will be achieved with all the related technologies designed to maximize output power and heat recovery from fuel cells and a monitoring system for maintenance purposes, This report describes the cur-rent state of the technology involved in each of these development targets.