Efficient energy utilization and management has been the major criteria in industrial and transportation sectors. Particularly, thermal energy management is the benchmark in various applications like automotive, energy storage, nuclear cooling, medical fields among others. Usage of microchannel devices to increase the thermal energy pose various disadvantages like high mechanical power requirement, frequent cleaning and sensitive to corrosion and fouling. Hence, nanofluids came into existence by dispersing high thermal conductive material in conventional base liquid to intensify the heat transfer rate. Hybrid nanofluids have higher thermal energy performance compared to mono nanofluids. In this research work, alumina-silica nanofluids were synthesized using 50% ethylene glycol by the two step method. The synthesized fluid was characterized using UV–Vis spectroscopy, SEM- EDS to confirm the size, shape and composition of nanoparticles. Zeta potential analysis was used to identify the particle size distribution and dispersion stability of the fluid. Experiments were carried out to find the overall coefficient of the nanofluids for various volume concentrations of 0.05%, 0.1% and 0.2% after determining its thermophysical properties. The percentage enhancement of overall heat transfer coefficient of nanofluid was 52.8% compared with the 50% ethylene glycol which implies that nanofluid can be used as a coolant to increase the thermal energy performance in various applications. © 2019 Elsevier B.V., All rights reserved.