Heat sinks are used in thermal management of the electronic devices such as supercomputers, data centres and batteries and fuel cells. Particularly, cooling requirements of microprocessors increase due to an increase in miniaturization and computational requirements. Efficient working of heat sinks is important to maintain certain temperature by dissipating heat to the environment. Development of efficient heat transfer mechanism is dependent on the highly conductive working fluids and heat transfer surfaces with high heat transfer coefficients. In the present investigation, four different geometries and three working fluids have been investigated to optimize the heat dissipation rate. In the present research, the thermal and hydraulic performance of heat sinks has been investigated. Experiments and numerical simulations have been conducted at different flow rates for different designs of heat sinks using water and CuO-, Al₂O₃-based nanofluids. Volume concentrations of 0.67% and 0.4% were used for Al₂O₃–H₂O and CuO–H₂O nanofluids, respectively, and 2.5 g each of aluminium and copper oxides nanoparticles were used. The simulated base temperature was 110 °C through mice element for the experimentation. Optimized configuration of the heat sink was obtained using water, and experiments were performed to examine the heat transfer enhancement using water and nanofluids. The main purpose of this investigation is to minimize the base temperature of the heat sink and to increase the heat transfer rate. The minimum base temperatures obtained for Al₂O₃–H₂O nanofluids and water were 43.4 °C and 45.2 °C, respectively, on the mini-channel heat sink with 0.5 mm fin spacing.