Abstract: An oxidant diffusion device for use in an axial flow tread carbon black reactor that is capable of providing improved uniformity in the physical and chemical profiles of the combustion gas produced in the combustion zone of a carbon black reactor. In one aspect, the oxidant diffusion device comprises a housing member having a distal end and a proximal end and further defining an internal cavity; an opening defined by the proximal housing end and in fluid communication with the internal cavity; a plurality of radial oxidant inlet apertures defined by the housing and in fluid communication with the internal cavity; and a plurality of axial oxidant inlet apertures defined by the distal housing end and in fluid communication with the internal cavity.