Abstract: The vaporization and thermodynamic properties of the NbO₂–TiO₂ system are studied by high-temperature differential mass spectrometry. The samples are evaporated from Knudsen effusion chambers made of tungsten. The partial pressures of the molecular forms of the vapor, the activities of the condensed phase components, the Gibbs energies, and the excess Gibbs energies are determined. It is established that the studied system is characterized by a negative deviation from the ideal behavior.