Three cubic equations of state are carefully examined to evaluate their capability for correlating the solubility of pure solids in supercritical mixed solvents. After obtaining the pure solute-solvent interaction parameters, the solid solute-cosolvent interaction parameters were directly calculated from the experimental ternary solubility data. The Redlich-Kwong, Soave, and Peng-Robinson equations of state correlate well the solubility data of 32 ternary systems producing AAD(%) errors of 12.54, 12.50 and 12.67% respectively.