The current study presents a numerical computation of combined gas radiation and forced convection through two parallel plates. A laminar flow of a temperature-dependent and non-grey gas in the entrance region of the channel was investigated. Over-heated water vapor was chosen as a gas because of its large absorption bands. Some special attention was given to entropy generation and its dependence on geometrical and thermodynamic parameters. The radiative part of the study was solved using the "Ray Tracing" method through S-4 directions, associated with the "statistical narrow band correlated-V (SNBCK) model. The temperature fields were used to calculate the distributions of local and global entropy generation. (C) 2008 Elsevier Ltd. All rights reserved.