The thermal lance process represents the oldest commercial use of oxygen cutting or piercing of massive objects (metallic materials and concrete). The thermal lance combustion model described in this paper has been developed on the basis of heat and mass transfer associated with iron (s)-oxygen (g) combustion reaction. The model includes metallic tube heat conduction and radiation, heat transfer by free convection to the external environment, and forced convection caused by the flowing gas in the lance body. The gas phase is described by a forced convection term and heat transfer from the metallic tube. The reaction term is included in boundary conditions. Experimental measurements have been carried out on an industrial size unit. A comparison with lance burning experimental data has been performed. The model shows lance temperature drops rapidly along the lance. The lance burning temperature has been predicted by the model, and the reaction kinetics of the iron combustion in oxygen has been discussed.