Abstract <p>The TERRA software package is used to perform thermodynamic modeling of the thermal decomposition of powdered ilmenite under low-temperature plasma conditions in the temperature range 300–6000 K. Argon and air are used as plasma-forming gases. Information on the properties of some components of the system under study is taken from the TERRA.props database. In addition, the thermodynamic properties of the condensed (solid and liquid) states of the compounds FeTiO₃, Fe₂TiO₄, Fe₂TiO₅, FeTi₂O₅, FeTi, and Fe₂Ti are added to the database, and the thermodynamic constants for Ti, TiO, Ti₂O₃, Ti₃O₅, TiO₃, Fe, Fe₂O₃, FeO, Fe₂N, and Fe₄N are corrected in accordance with the literature data. The results of thermodynamic modeling are used to calculate the temperature dependences of the component contents in the condensed and gas phases and to identify the regions of their existence. FeTiO₃ is found not to decompose on heating in an argon atmosphere in the temperature range 300–1200 K. When the temperature increases, Fe₂TiO₄ (1300–1600 K), FeTi₂O₅ (1300–1900 K), and FeO (1600–1900 K) can form. At <i>T</i> ≥ 2000 K, FeTiO₃ and FeTi₂O₅ form. When ilmenite is heated by an air plasma jet, double oxides Fe₃O₄, TiO₂, and Fe₂O₃ and triple oxides FeTi₂O₅, Fe₂TiO₅, and Fe₂TiO₄ can form in a condensed phase along with ilmenite. The modeling results will be used to develop a technology for producing an ilmenite powder in an arc plasma reactor.</p>