An experimental study has been carried out to investigate the thermal performance of different types of heat sink made up of Copper based metal matrix composite (MMC) with reinforcement of CNT of 2.5%, a aluminium alloy (6061- T6), and aluminium pure metal. By this, we can have a fair comparison between a metal, alloy and a composite. Air is used as cooling medium inside a wind tunnel where the heat sink is heated with the help of a Mica plate type heater. Temperatures reading are taken with the help of set of thermocouples at each and every conditions of flow. The experimental performance parameter which includes Nusselt number and fanning friction factor are calculated for Reynolds numbers in range of 890 to 4667. Based on the Nusselt number calculated for Q =40W, it showed better heat transfer performance for Aluminium heat sink and Aluminium Alloy heat sink, respectively. Also, the second performance parameter i.e. fanning friction factor showed much greater value for composite heat sink as compared to other two.