The placement of porous materials in passages can enhance the transfer of heat to a flowing fluid. Porous passages are useful devices for cooling of engineering systems. There has been a current interest in utilization of porous passages for electronic cooling applications. In this study, forced convective heat transfer in a vertical square channel symmetrically heated with a constant heat flux, and packed with saturated porous media, has been investigated theoretically and experimentally in the present work. The porous media was made with spherical glass particle of four different diameter (3, 5.6, 12 and 15.4 mm), in a range of porosity (0.38<ε<0.533). The water flow in the packed channel was assumed to be hydrodynamically fully developed, and the effect of inertia in the momentum equation is negligible.