A catalytic combustor is described for a 1.5 MW gas turbine engine. The catalyst temperature is limited and the high combustor outlet temperatures required by the turbine are generated downstream of the catalyst. The combustor design places a low NOx prebumer upstream of the catalyst and uses this preburner to achieve optimum catalyst operation by providing the desired catalyst inlet temperature. The combustor system employs the catalyst during engine acceleration and loading. The catalyst design has been tested on a sub-scale rig under full pressure and flow conditions simulating turbine operation over the entire operating range including acceleration and loading. The design should achieve emissions at full load operation of <3 ppm NOx and <10 ppm CO and UHC. Low emissions operation is expected over the 75-100% load range. In addition, long-term sub-scale rig test results are reported at simulated full load operating conditions including cyclic operation and full load trips.