The efficiency of the application of high-emissivity coatings on reactor tubes and furnace walls in steam cracking technology can only be evaluated based on a correct description of the radiative heat transfer in the furnace. For the flue gases, a banded gas radiation model is introduced; for the surfaces a non-grey surface approach is applied. For the same total heat input, a thermal efficiency rise of over 5% is calculated for a naphtha cracking furnace under normal operating conditions. (C) 2004 Elsevier Ltd. All rights reserved.