Solubility of solids was modeled in modified supercritical carbon dioxide as a predictive method. The Peng-Robinson equation of state was used to characterize the ternary systems using the one-fluid van der Waals rides. Ternary, mixture parameters k(12), k(23), and k(13) were obtained from the binary mixtures using Wong-Sandler mixing rides or the linear combination of Vidal-Michelsen mixing rules together with UNIFAC as required as a fully, predictive tool for the liquid activism coefficients. When this method was applied to predict the solubility of beta-naphthol in CO2 modified with 6% and 10% toluene, values for the predicted solubility were very similar to the measured ones, with deviations of 9.6 and 26.3%, respectively. However when the method was applied to the data of Simon et al. who examined six common cosolvents, the results were not as good in absolute terms, but the solvents were sorted in about the same order as found experimentally. The method provides quite an approximate guide to judge the most effective cosolvent from several candidates using a fully, predictive methodology.