Thermodynamic behavior of N in the Fe–Cr–Mn–C–N liquid solution is modeled using the Modified Quasichemical Model with consideration of the short-range ordering. A set of new model parameters for the Fe–Cr–Mn–C–N liquid solution are determined based on a critical evaluation of the available experimental data. The solubility of N in the entire composition range of all binary, ternary, and multicomponent molten alloys within the Fe–Cr–Mn–C–N system is well optimized for various temperatures and N₂ pressures. Besides, thermodynamic properties of N in Fe-based liquid solution affected by the alloying elements are calculated from the developed thermodynamic database. As an application of the database, the N solubility in different steel melts of various conditions is predicted for the process optimization.