The Peng-Robinson equation of state (EOS) with the classical van der Waals quadratic mixing rules is used in this study to calculate the solid solubilities of polycyclic aromatic and long chained hydrocarbons in supercritical carbon dioxide, ethane, and ethylene. The effect of the binary interaction parameters k(ij) (for parameter a) and l(ij) (for parameter b) in the van der Waals mixing rules, on the pressure dependence of the solute solubility in the supercritical fluid is examined. The addition of a third parameter, lambda(2), that modifies the pure component covolume parameter b of the solute, significantly enhanced the ability of the EOS to fit the experimental data. Reasonable optimally fitted binary interaction parameters k(ij) and l(ij) and pure component parameter lambda(2) were obtained. The EOS parameters were correlated with molecular properties and can be used as estimates for predicting solubilities when experimental data is missing. A phase stability test is proposed to guarantee that the stable root is always chosen in each case, when the solubility problem presents multiple solutions.