The knowledge of the solubility in pure solvents and solvent mixtures is crucial for designing the crystallization process. However, it is practically impossible to scan all possible solvent mixtures and mixture compositions experimentally. Therefore, a physically well-founded thermodynamic model which allows for solubility predictions in pure solvents and solvent mixtures based only on a small amount of experimental data is required. In this work, we demonstrated the applicability of the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state to model and to predict the solubility, especially of pharmaceuticals and complex (bio-) molecules, in pure solvents and solvent mixtures.