Abstract The method of pulse heating for the study of thermophysical properties for oil/refrigerant solutions in a wide temperature range and for monitoring of an actual state of these systems has been developed. The regimes of linear heating and thermostabilization of the superheated probe are applied for solving our task. The objects of study are as follows: synthetic oils Mobil EAL Arctic 22, PLANETELF ACD22, XMPA, and solutions of carbon dioxide in these oils. The upper boundary, with respect to temperature, of the two-phase equilibrium region including the vicinity of the liquid–vapour critical curve of these systems, gas solubility in oils at various temperatures, short-time thermostability, and thermal conductivity of oils are considered. Inclusion of the thermally unstable states of a substance in investigation allows one to essentially extend the set of compared data.