The M-1 model has been extended to analyze the radiative heat transfer in the 1-D and 2-D enclosures containing absorbing, emitting, and scattering medium. The governing differential equations for the M-1 model were solved numerically by the central difference technique instead of the Harten-Lax-van Leer-Einfeld type approximate Reimann solver used in the previous studies. The predictive accuracy of the model was tested by calculating both an infinite parallel plate and an infinite concentric cylindrical enclosure for 1-D test cases. In addition, the 2-D rectangular gray semitransparent media were also studied to test the predictive accuracy of the M-1 model and then they were compared to the benchmark solutions available in the literature. The results of the M-1 model were found to be in good agreement with the exact results of the studied cases. (C) 2014 Elsevier Masson SAS. All rights reserved.