In this paper we report about the procedure for investigating the thermal properties of three-component water-in-oil microemulsions exhibiting a percolative behavior. The thermal properties of these highly disperse systems are analyzed both on freezing the liquid samples and upon their melting. A thermal cycle suitable for evidencing the higher order phase transition at the percolative threshold temperature is presented. Since the latter transition was found to depend on the system's thermal history, a modification of the DSC set up is described that allows the refilling of the liquid nitrogen Dewar without requiring the removal of any of the instrument parts and enables to maintain the calibration assessment through long time lasting measuring runs. The change in the specific heat, at constant pressure, at the percolation transition was evaluated. The thermal hystheresis associated with the transition is also discussed.