The selection of the extractant is an important consideration for the design of liquid–liquid extraction processes. Researchers are paying more attention to a priori predictions of liquid–liquid equilibria. The predictive and fully open-source thermodynamic model COSMO-SAC (conductor-like screening model-segment activity coefficient) uses quantum chemical calculations for calculating activity coefficients and thermodynamic properties. Through a brief review of the recent advances of COSMO-SAC in predicting liquid–liquid equilibrium of ionic liquid systems, this work assessed the accuracy of prediction for different chemical family combinations and generated directions for future improvement.