The possibility of calculating the thermodynamic properties of glass melts in the Cs₂O-B₂O₃-SiO₂ system with the use of the vacancy variant of the generalized lattice theory of associated solutions is demonstrated. A comparison with the experimental thermodynamic functions previously determined by high-temperature mass spectrometry shows that the calculations performed within this approach lead to reliable thermodynamic functions for glass melts in the Cs₂O-B₂O ₃-SiO₂ system.