Abstract: A simplified geometrical model of high porosity open-cell metal foams was constructed. A related expression of effective thermal conductivity of the metal foams was derived on the base of the analogy between thermal and electrical resistance at the scale of unit pore. The correlation was further modified by existing experimental data. In addition, convective heat transfer was numerically simulated for air flow in a metal-foam filled three-dimensional rectangular duct. The simulation results were analyzed and compared with experimental data. It is shown that the calibrated effective thermal conductivity model is applicable for aluminium metal foams. Under the condition of the same porosity, the convective heat transfer of forced flow in the duct is enhanced by using higher porosity (i. e. smaller pore size) metal foams, but at the expense of a higher pressure drop. To some extent, metal foams with a lower pore density have a better overall performance on convective heat transfer.