This paper numerically examines natural convection in a square enclosure in which two porous media are separated by a vertical solid wall. The effects of pertinent parameters such as location, thickness and thermal conductivity of the solid wall on the flow and temperature fields as well as the heat transfer rate of the enclosure are studied. Moreover, the effects of effective heat transfer coefficient and permeability of both porous media on the results are investigated. The analysis is based on a control volume approach in which the non-dimensional governing equations simulating the fluid behaviour in the enclosure are solved. The vertical walls of the enclosure are maintained at different temperatures while the horizontal walls are thermally insulated. The results show that a higher heat transfer rate is achieved as the solid wall moves away from the centre of the enclosure. Moreover, at high Rayleigh numbers, the heat transfer rate increases as the thickness of the solid wall increases. It is also shown that the thermal conductivity and permeability of the solid wall affect the heat transfer mechanism within the enclosure