Solid oxide fuel cells (SOFCs) are expected to be applied to Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC). However, most SOFC modules are designed with natural gas as fuel that means SOFC modules are cooled using the internal reforming reaction (endothermic reaction) of natural gas. In this research, a modified SOFC module manufactured by Mitsubishi Hitachi Power Systems, Ltd. (MHPS) was installed and power generation performance with assumed gas was verified. As a result, it was confirmed that the output of SOFC module was reduced by changing the fuel from natural gas to assumed coal gas. On the other hand, improvement of SOFC performance was possible by changing the operating conditions. In this paper, operation test results are introduced.