Thermal management of electronic systems is investigated with a hybrid thermosyphon assisted thermal energy storage system. Various circulating coolants namely DI water, acetone, methanol and ethanol are used in this work. The heat input to the system varies between 50 and 90 W. Lauric acid is used as phase change material (PCM) and stored in an annular which helps to remove heat from the vapourized coolants. The molten PCM is then solidified by supplying cold water through a copper tube when the power is switched OFF. The influence of heat input on heat transfer performance such as percentage of heat removal, heat transfer coefficient (HTC) and thermal resistance of various circulating coolants is analysed. In addition, the temperature variation during the charging and discharging performance of PCM is studied by the effect of different coolants at a given heat flux. Results show that (i) the maximum percentage of heat removal and HTC of about 98.9% and 205.78 W/(m2.K) are obtained for acetone at 90 W due to low boiling point, low latent heat of vapourization (LHV), low viscosity and less effect on subcooling (ii) the low thermal resistance of acetone is 0.316 K/W owing to the high vapour flow rate at maximum heat input (iii) PCM attains steady state temperature at a faster rate and the maximum thermal power absorbed is about 6.18 W when the acetone is used as a circulating coolant at 90 W. © 2019 Elsevier Ltd