Abstract: In a catalytic combustor for gas turbines, the dimensions of the preheater and premix duct, the location of the preheater and premix fuel nozzles, and the number and location of air orifices in the combustor can inner liner are configured to result in low NOx production during both preheating combustion and catalytic combustion. Placement of the air orifices helps reduce the potential for autoignition within the premix duct, while enhancing fuel-air mixture uniformity upstream of the catalyst. At the same time, the overall configuration is optimized to result in the relative compactness of the catalytic combustor, making it particularly suitable for applications such as automotive turbine engines and microturbines.