Minichannel heat sinks are widely adopted heat dissipation solutions from miniaturized heat flux generating components, such as microprocessors. This paper presents further enhancements in the thermal and hydraulic performance of a minichannel heat sink by employing supercritical carbon dioxide (sCO 2) as a coolant. In this study, thermal and hydraulic performance of CO 2-cooled minichannel heat sink at three inlet pressures (P i n, C O 2)(ie, 8.0, 10 and 12 MPa) and inlet temperatures (T i n, C O 2) ranging between 30∘ C− 60∘ C is compared with a water-cooled minichannel heat sink at inlet conditions (0.1 MPa, 30° C− 38° C). To investigate the performance of the minichannel heat sinks, a conjugate heat transfer model is solved in a commercial code ANSYS-CFX. Whereas the variations in thermo-physical properties of supercritical carbon dioxide (sCO 2) are incorporated in ANSYS-CFX through a real gas property (RGP) table. The results reveal a maximum enhancement of 42.13% in average heat transfer coefficient (h¯) for minichannel heat sink using CO 2 as a coolant at inlet conditions of 8.0 MPa and 34∘ C. Similarly, a pressure drop reduction of 55.79% is computed for CO 2 as a coolant at corresponding inlet conditions as compared to water-cooled minichannel heat sink. Moreover, the results suggest that replacing water with CO 2 as a coolant at higher inlet pressures (P i n, C O 2) ie, 10 MPa and 12 MPa can further reduce pressure drops in the minichannel heat sink by 60.65% and 62.41%, respectively. Apart from the lower base temperatures, performance evaluation criteria (P E C) suggests that the overall performance of the minichannel heat sink using CO 2 at 8.0 MPa is roughly enhanced by 2 times as compared to water-cooled minichannel heat sink.