Radiative integral transfer equations for a rectangular participating and isotropically scattering inhomogeneous medium are solved numerically for the incident energy and the net partial heat fluxes using the method of "subtraction of singularity". All the relevant single (surface integrals) and double integrals (volume integrals) are carried out analytically to reduce the computation time and numerical integration errors. The resulting system of linear equations are solved iteratively. A benchmark problem is chosen as a rectangular inhomogeneous cold participating medium which is subject to externally uniform diffuse radiation on the bottom surface. Solutions for linearly and quadratically varying scattering albedos are provided in tabular form. (C) 2003 Elsevier Ltd. All rights reserved.