A new thermodynamic model was developed for modeling the solubilities of solid solutes in supercritical carbon dioxide. The model combines the cubic Patel-Teja equation of state (EOS) with the Wong-Sandler (WS) mixing rules (MR). The model is applied to correlate the solubilities of different ternary systems and the corresponding binaries. The versatility of this model is indicated by the ability of the model to successfully predict the solubilities of both polar and non-polar mixtures. The model provides a better correlation than the conventional models that use Peng-Robinson-EOS (PR-EOS) with simple or WS MR.