Catalytic combustion is an advanced combustion technology and is effective as a NOx control for a 1300 degrees C class gas turbine for power generation, but the catalyst reliability at high temperatures is still insufficient. To overcome this difficulty, catalytic combustors combined with premixed combustion were designed. In this concept, it is possible to obtain combustion gas at a temperature of 1300 degrees C while keeping the catalyst bed temperature below 1000 degrees C. Catalyst segments are arranged alternately with premixing nozzles for the mixing of catalytic combustion gas and fresh premixture. An air bypass valve was fitted to this combustor for extending the range of stable combustion. As a result of the atmospheric combustion tests, NOx emission was lower than 5 ppm, combustion efficiency was almost 100%, and high combustion efficiency was obtained in the range of 900-1300 degrees C of the combustor exit gas temperature. A full-pressure combustion test is planned to prove the combustor performance.