One of the reasons for depletion of the ozone layer of the atmosphere is the use of materials in different industrial brands which have disintegrating effects on ozone in their compositions. It is known that thermodynamic analysis of the operating processes of machines and systems that use heat energy depends on calculations of the heat transfer processes of parts of the system and choices of the thermohydrodynamic regimes and parameters. In this study, an experimental investigation is conducted on the thermal properties which are close to the curves of liquid and two phase boiling and condensing of two new fluid couples for absorption cooling systems, and absorption heat pumps which are better ecologically. The obtained results are analyzed, and new equations are given. Experiments are done for methanol-LiBr and methanol-LiCl solutions with changes of pressure, changes of temperature and concentrations of solutions in the ranges of 0.1-40 MPa, 298-498 K, 2-12%, respectively. During the experiments, extreme care is taken to keep the solution concentration stable, and the obtained results are analyzed in different thermodynamical coordinates. State equations are constructed according to the values of specific volume, and the main thermodynamical properties are calculated with the use of the differential equations of thermodynamics. Values related with these calculations are given in tables. (C) 2000 Elsevier Science Ltd. All rights reserved.