Three cubic equations of state are carefully examined to evaluate their capability for correlating the solubility of solid mixtures in supercritical fluids. After obtaining the pure solute-solvent interaction parameters, the solute-solute interaction parameters were directly calculated from the experimental ternary solubility data. The Redlich-Kwong, Soave, and Peng-Robinson equations of state correlate well the ternary data. However, the Redlich-Kwong equation of state gives the best result among them.