A two-dimensional modeling is performed to study natural convection coupled with radiation in a square cavity partially heated from one vertical side and cooled from above. The simulation of flow and heat transfer is achieved by adopting the MRT scheme of the Lattice-Boltzmann method. In this work we focus on qualitative and quantitative effects engendered by the coupling between the surface radiation and natural convection in the studied configuration. The obtained results are presented in terms of streamlines, isotherms, heatlines and average Nusselt number. This preliminary study shows that the MRT-LBM method can be used to simulate faithfully the heat transfer by natural convection coupled to radiation. The contribution of the radiation to heat transfer should be considered since its effect is far from negligible, even more; it outweighs that of convection depending on the value of Rayleigh number. (C) 2017 The Authors. Published by Elsevier Ltd.