The aim of the present work is to develop a numerical scheme to investigate the combustion performance of porous burner. The finite volume method for three-dimensional Navier–Stokes equations, energy equations, and chemical species transport equations are solved and heat release described by a multi-step kinetics mechanism. The simulated results for temperature profiles are compared with published experimental data and a good agreement is observed. Predicted 3D temperature fields are also presented and the effects of material’s grain size and flow characteristics including excess air ratio on flame characteristics are investigated. It is observed that temperature profiles, gas velocity, and convective heat transfer between solid and gas phases are affected by the perturbations associated with these parameters.