Abstract In this study, dimethyl adipate, an organic ester, as the phase change material (core) was microencapsulated into melamine-formaldehyde (shell) in different shell-to-core ratios using in-situ polymerization technique. The microencapsulated phase change material suspensions (MPCMS) were prepared through the dispersion of microcapsules in appropriate proportions into the carrier fluid. The surface morphology of the prepared microcapsules were observed to be almost spherical. The microcapsules with low crystallinity offered greater resistance towards crack, which was attributed to the flexible structure of the shell. Surface structure studies has confirmed the chemical stability between the core and shell. In addition, the microcapsules exhibited good latent heat enthalpy of around 53 kJ/kg and 70 kJ/kg and they were thermally stable up to 160 °C. Furthermore, the viscosity of MPCMS was found to be very low, which enabled them to exhibit Newtonian flow behaviour. Thus, the test results have signified the MPCMS to be considered as a viable candidate for cool thermal energy storage application.