Kawasaki Heavy Industries launched the L20A gas turbine, rated at 18MW, in 2001. The design philosophy adopted for the turbine includes a high efficiency transonic axial-flow compressor with eight can-type combustors and a high turbine inlet temperature of 1250 Deg C. This results in a thermal efficiency of 35%, an electric efficiency of 50% for combined cycle power plants and an overall thermal efficiency of 81% for cogeneration systems. In addition, the NOx emissions from the combustor are lower than 23 ppm and the engine has a long service life. These features permit long-term continuous operations under various environmental limitations. Details are presented in 2002-GT-30255.(1) The first commercial unit has been in operation as a daily start and stop cogeneration plant in Kawasaki’s Akashi Works in Japan since October 2001. Accumulated operation hours are 5500 hours and 410 starts as of March 2004. Reliability higher than 99% has been demonstrated during this period. During the shop test and the commercial operation, some additional improvements have been developed for the compressor, turbine and combustor.