In this work, thermodynamic functions of evaporation of copper chalcogenides (Cu2S, Cu2Se, and Cu2Te) are determined via previously published data and thermodynamic values obtained by the authors of the work. The obtained results indicate a very low probability of separation of compounds into copper and chalcogen by dissociation under vacuum-thermal processing conditions. Liquid-vapor phase transitions in binary systems Cu2S – Cu2Se, Cu2S – Cu2Te, and Cu2Se – Cu2Te at low pressures of 15 and 0,7 kPa are constructed based on the vapor pressure of copper chalcogenides. It is shown that the pressure eases over the liquid bath impairs the separation of chalcogens, therefore separation in one stage by thermo-vacuum treatment at a pressure of 0,7 – 15 kPa is not possible
