Laminar methane-air diffusion flame was simulated by coupling a method of lines based parallel direct numerical simulation code with a radiation code based on method of lines solution of discrete ordinates method. The predictions of the code are validated against experimental data as well as numerical results of the same code without radiation model. Comparisons show that incorporation of radiation code to the computational fluid dynamics code results in a significant improvement in the predicted temperatures. Transient results exhibit the physically expected trends. The coupled code is a promising tool for the simulation of transient reacting radiating flows. (c) 2006 Elsevier SAS. All rights reserved.