Colorless distributed combustion (CDC) has been shown to provide significant improvement in gas turbine combustor performance. Colorless distributed combustion with swirl is investigated here to develop ultra-low emissions of NO and CO, and significantly improved pattern factor. Experimental investigations have been performed using a cylindrical geometry combustor with swirling air injection and axial hot gas exit stream from the combustor. Air was injected tangentially to impart swirl to the flow inside the combustor. The results obtained from the combustor have demonstrated very low levels of NO (similar to 3 PPM) and CO (similar to 70 PPM) emissions at an equivalence ratio of 0.7 and a high heat release intensity of 36 MW/m(3) -atm under non-premixed combustion. To further simulate gas turbine operating conditions, inlet air to the combustor was preheated to 600 K temperature and the combustor operated at 2 atm pressure. Results showed very low levels of CO (similar to 10 PPM) but the NO increased somewhat to 10 PPM at an equivalence ratio of 0.5 and heat release intensity of 22.5 MW/m(3)-atm under non-premixed combustion conditions. For premixed combustion, the combustor demonstrated low levels of both NO (5 PPM) and CO (8 PPM) at an equivalence ratio of 0.6 and a heat release intensity of 27 MW/m(3)-atm. Results are reported at different equivalence ratios on the emission of NO and CO, lean stability limit and OH* chemiluminescence. These results suggest that further performance improvement can be achieved with improved fuel mixture preparation prior to the ignition of fuel at higher operational pressures using swirling combustor design for our quest to develop ultra low emission high intensity combustor for gas turbine application. (C) 2011 Elsevier Ltd. All rights reserved.