Experiments have been carried out to investigate the heat transfer characteristics of an aluminum-foam heat sink placed on a heat source in a channel. The thermal performance of aluminum-foam heat sinks is evaluated in terms of the Nusselt number and thermal resistance of the heat sinks. The pore density of the aluminum-foam heat sinks and the Reynolds number are varied in the range of parameters: 10, 20, 40 pores per inch (PPI) and 710≤Re≤2900, respectively. It is found that thermal resistance is substantially reduced by employing an aluminum-foam heat sink with low pore density due to the relatively intense airflow through the heat sink. The aluminum-foam heat sink may provide 28% or higher thermal performance than a conventional parallel-plate heat sink of the same size. Further, the aluminum-foam heat sinks can dramatically reduce the overall mass of electronics-cooling devices owing to high porosity.