Petroleum cokes (PC) is a by-product from the oil refining process. In recent years, deep drawing oil technology has been developed and surplus PC with low volatility and low quality is increasing in the market. If the surplus PC could be used as the main fuel for thermal power stations, it will become most economical fuel in the next 5 to 20 years. Mitsubishi Heavy Industries, Ltd. constructed the thermal power station with a 100% PC firing boiler for Frontier Energy Niigata Co., Ltd. Commercial operation started in July 2005. This power station is highly praised both in Japan and foreign countries as a large boiler with the stable combustion of 100% PC, while most of the boilers with PC firing needs heavy fuel or other fuels for stable combustion. This report states the distinctive technology for a thermal power station with a 100% PC firing boiler, including the results of continuous operation and first maintenance in April 2006.