Abstract: A combustion head for a fluid fuel, particularly a liquid fuel, which is burnt particularly in the presence of a gas having an oxygen concentration substantially less than that of air, comprises, adjacent to the actual burner, a generally cylindrical box containing an inlet aperture designed to create a substantial pressure drop on injecting the oxygen-containing gas into the box, and a disc situated at the outlet of the box and dimensioned to create a second and lower pressure drop. The intense combustion produced in the box heats its walls to a temperature substantially above the final point of the distillation curve for the fuel, so preventing coke deposition.