In this study, the natural and forced convection heat transfer in an enclosure with vertical heated block and baffles are experimentally and numerically investigated. The enclosure walls are kept as adiabatic, and the heating block contains extended baffles and receives heat flux. The effect of heat flux, Reynolds number and baffle configuration on the heat transfer characteristics and flow behaviour inside the enclosure is examined. The configuration parameter for natural and forced convection involves three heating block models, namely, block without baffle (plain), block with baffles and block with partially cut baffles. The widths of baffles are 2.5, 5 and 10 cm for the block with baffle case, and the width of partially cut baffle is 5 cm. The heat flux (q) ranges from 240 w/m2 to 1425 w/m2 for all the models. The Reynolds number (Re) ranges from 5650 to 15950 for forced convection heat transfer. In the numerical part, a finite volume method (via Ansys Fluent) is used to solve the governing equations. Result shows that the increase in baffle width has no remarkable effect on the heat transfer, and the partially cut baffles provide an enhancement of approximately 30% compared with the plain heating block. The baffle cases have an evident effect in reducing the block surface temperature by approximately 11% compared with the plain case at Re = 0 and q = 240 w/m2. Empirical correlations for the block with baffles are obtained for each heat flux to predict the average Nusselt number.