Thermodynamic properties of Y2O3·Cr2O3 were determined by means of electromotive force (emf) measurements using stabilized zirconia as a solid electrolyte at 1182 -1386 K. The constructions of oxygen concentration cell was Mo|Cr, Y2O3, Y2O3·Cr2O3|ZrO2(+MgO)|Cr, Cr2O3|Mo Using the emf values and its temperature dependences of the above cell, the standard free energy of formation of Y2O3·Cr2O3 according the reaction Y2O(3(s))+Cr2O(3(s)) = Y2O3·Cr2O(3(s)) was obtained as△G0((Y2O3)·cr2o3) = 39160- 34.97T( error in experiment is±350 cal/mol) or △G0((Y2O3)·cr2o3)= 163900-146.3T (error in experiment is±450J/mol) According the linear equation △G°= a + bT and equation △G = △H - T△S, the average enthalpy and entropy in the temperature ranges of investigation may beassumed as △H0((Y2O3)·cr2o3) = 39160 cal/mol or 193900J/mol, △S0((Y2O3)·cr2o3) = 34.97 cal/(mol ·K) or 146.3J/(mol·K).