Abstract: A system for reducing the formation of NO.sub.x pollutants during the combustion of liquid fuel in a gas turbine engine. The system comprises introducing an externally modulated, rapidly-pulsed, oscillated or sinusoidal fuel flow delivery rate (generically referred to as "modulated") to produce a controlled degree of combustor air input flow oscillation and bulk flow oscillation within the combustor which enhances the fuel-air mixing rate and homogeneity within the combustor, decreases the residence time of transition fuel/air mixtures prone to NO.sub.x formation, and substantially decreases the NO.sub.x concentration in the resulting combustion gas product without creating a net pressure gain throughout the combustion chamber.