Mitsubishi Materials Corporation (MMC) and The Kansai Electric Power Co., Inc. (KEPCO) have been collaborating to develop intermediate temperature SOFC (IT-SOFC) modules, which use lanthanum gallate based electrolyte, for stationary power generation since FY2001. The fourth generation 1-kW class module with internal manifolds was developed and the electrical efficiency of 54% HHV on DC output was achieved in 2005. The long-term durability test of the 1 kW-class module was conducted. The degradation rate of the terminal voltage was about 0.5% per 1,000 hours. In order to test the durability of the module against variation of operating conditions, the cyclic loading experiments were conducted. As a proof of concept for a multi-stack module, the 10 kW-class module has been designed and manufactured. In evaluation tests, the module achieved the electrical efficiency of 50%HHV with 12.6 kW-DC output power at thermally self-sustained operation using town gas. Another program to increase the output power density of cell-membrane has been started with optimizing the electrolyte, fuel and air electrodes, and the current collectors.