The paper describes recent developments of advanced combustion techniques for control of NOx and/or SOx for coal-, oil-, and gas-fired systems. Stationary combustion sources, particularly those fired with coal and oil, are major sources of NOx and SOx emissions. The commercially available combustion modification technology is relatively low cost; however, it gives a limited degree of control. Advanced combustion modification techniques are being developed which have the potential for greater NOx control effectiveness. The development of new or improved combustion systems is based on an understanding of the basic processes of NOx formation and control.