Mitsubishi Power, Ltd. (Mitsubishi Power) started rated operation of the world's first 1650°C-Class JAC gas turbine in 2020. This gas turbine successfully achieves a higher turbine inlet temperature by further increasing the thickness of the highly reliable Thermal Barrier Coating (TBC) utilized for the 1600°C-Class J-Series gas turbine in order to improve the thermal barrier capability. After confirming the high spalling resistance of this advanced TBC in element tests and a sufficient amount of validation work with an actual J-Series turbine, we started the validation process with the JAC-Series, which has so far operated for about 2,000 hours and demonstrated excellent results.