Abstract: An air-cooled oxygen-gas burner for use with a direct fired furnace. The burner comprises a body formed from three concentric metal tubes supported in a cylindrical housing secured about a conical bore in a refractory side wall of a furnace. The three concentric tubes have a cone shaped inner end which are adjustable to define a nozzle with annular openings therebetween of variable size to vary the shape of a flame produced by a mixture of combustible gas, oxygen and air fed under pressure, respectively, in each of two chambers defined between the three concentric metal tubes and a chamber defined between the tubes and the cylinder housing. The combustible gas is fed in the inner chamber, the oxygen in the intermediate chamber, while the air is fed in the outer chamber to cool the concentric tube assembly and the furnace refractory about the burner nozzle.