A thermodynamic evaluation on the Fe-M-O (M= Al, Cr, Mn, Si, Ti) ternary systems has been made in order to compile a thermodynamic database for steel systems so that the stabilities of various oxides in steels can be calculated. The calculated oxygen solubility limits at 1600℃ in Fe-M melts showed satisfactory agreements with relevant experimental information. The range of oxygen potential suitable for bright annealing of an austenitic stainless steel was also calculated based on a criterion that SiO₂ should form on the steel surface before the formation of Cr₂O₃. and showed a good agreement with experimental information. Based on the good agreements between calculations and relevant experimental information, it was concluded that the current thermodynamic database enables the calculation of stabilities of various oxides over a wide composition and temperature range in steels with good predictability.