In an air-staged diffusion nozzle for a gas turbine combustor, air is mixed with the gas fuel and expanded in a downstream burner tube. Introduction of air, passing downstream from the tip of the nozzle to the burner tube space forces hot gases away from and cools the nozzle tip. Air flow through an inner swirler or through cooling holes on the nozzle tip may be arranged to establish a cooling flow volume and direction that advantageously interacts with gas fuel-air flow from an outer swirler to improve fuel-air mixing in the burner tube, helping to reduce emissions and soot formation.