Experimental study has been conducted to analyze the heat transfer performance of two different configurations of the double layer microchannel heat sinks. Parallel rectangular channels are used in the bottom layer of the both heat sinks whereas; upper layer consists of rectangular channels and pin fins. Comparative investigation has been done where single phase deionized liquid water is used as the coolant. Heat flux was varied from 80-500 kW/m² and Re ranges from 350-950. Results obtained in terms of the important performance parameters including heat transfer coefficient, heat sink's bottom wall temperature, Nusselt number show that both the heat sinks are deliberating almost equal thermal performance. Although for the given ranges of operating parameters, heat transfer performance of conventional double layer heat sink was found slightly better as compared to the double layer heat sink possesses pin fin at the upper layer. Average value of Nusselt number was 3-5% higher in conventional configuration however, it experiences higher pressure drop by 5-10% as compared to the finned configuration.