Abstract: A thermodynamic calculation model for the iron oxide reduction reactions was established based on the most recognized thermodynamic data of the pure substances. According to the model calculation， scattered accurate thermodynamic data of the balance reduction potential and the standard Gibbs free energy of the iron oxide reduction reactions were obtained depending on temperatures. With the mathematical simulation software Lingo 11， sixteen equilibrium GT formulas of the iron oxide reductions were fitted under the thermodynamic constraint of the BaurGlaessner diagram. Eight enthalpy change data at 298K for the reactions were also given. Results show that the eutectoid temperatures of the iron oxides reduced by CO and H2 are both 576℃， and the corresponding equilibrium reduction potentials are 5070% and 7583%， respectively. The reducibility transition temperature of CO and H2 is 819℃.

Key words: iron oxides, reduction, thermodynamics, Lingo, optimized fitting, enthalpy change