Molten carbonate fuel cell (MCFC) power generation systems will provide a number of merits such as high efficiency, various fuel choices (coal, LNG, methanol), fast load response, and clean exhaust gas to the electric utilities. In order to realize such attractive power sources, it is important to develop not only high-performance large cells and stacks but also suitable system control technologies. The Central Research Institute of Electric Power Industry has recently constructed a 10-kW-class MCFC power generation system test facility and started a series of stack and system tests. Using 10-kW-class MCFC stacks, CRIEPI has clarified those thermal characteristics and gas recycling performance. One of those test results show a 53% energy conversion efficiency with anode gas recycling only.