The solubility of xylenol isomers, dimethylnaphthalene isomers, naphthol isomers, and anthracene and phenanthrene in supercritical carbon dioxide is calculated by the Predictive Soave-Redlich-Kwong (PSRK) equation of state proposed by Holderbaum and Gmehling. The UNIFAC group interaction parameters used in this model are modified to distinguish solubility of the isomers using radial distribution functions, g(mn)(r), of supercritical carbon dioxide around the sites of the isomers calculated from Monte Carlo simulation. The calculated solubility of isomers is improved by using the modified parameters.