High performance cooling anticipated in smaller size heat transfer equipment is the most significant challenge in many industries including CPU cooling, refinery, petrochemical, power stations, automobiles, etc. Nanoliquids are a new class of thermal fluids for better heat transfer rate and least energy consumption. In this work, cupric oxide/silica hybrid nanoliquids are synthesized using water as base fluid. The synthesized nanofluids are characterized using X-Ray Diffraction, Transmission Electron Microscopy, Selected Area Electron Diffraction and Scanning Electron Microscopy—Energy-Dispersive X-ray Spectroscopy analysis to confirm their crystal structure, size, shape and elemental constituents. The stability was analyzed using Zeta potential instrument and their thermophysical properties were measured for various temperatures and concentrations. The hybrid nanoliquids are circulated into the jacketed vessel to extract the heat from the fluid inside the vessel. Using the measured properties and the temperatures of fluid inside the vessel and jacket side, overall heat transfer coefficient was calculated for the nanofluid and conventional coolant and the results are compared. Results indicate that heat transfer is directly proportional to flow rate and volume concentration and it was found that 48.6% enhancement in overall heat transfer coefficient was achieved for 3 LPM flow rate at 0.2% concentration. © 2025 Elsevier B.V., All rights reserved.