A new combustion catalyst system for gas turbines composed of high-temperature durable ceramic catalysts made of fine manganese-substituted hexaaluminate particles and noble metal-carrying cordierite honeycomb catalysts has been developed. A 160 kW prototype catalytic combustor turbine rigged with a 220 mm in diameter catalyst system was constructed and tested including a continuous 215-hour operation and repeated sudden stops. The results showed practical combustion performance with ultra-low NOx emissions less than 40 ppm (converted to 0% oxygen) and the feasibility of long term catalyst durability.