The solubility of less volatile substances in supercritical fluids can be predicted by thermodynamic relations of solid-gas and liquid-gas equilibrium. For the prediction, it is necessary to utilize the equation of state which can represent accurately the supercritical state of mixture composed of gas and less volatile matter. In present work, the solubility is calculated by using the equations given by Peng-Robinson and Soave that are relatively simple and accurate. It is shown that the observed data to be available in literature may be well correlated by using thermodynamic relationships and the equations of states mentioned above. We present also the values of interaction parameter included in the equations. The effect of enhancement factor（E） on temperature and pressure is discussed. It is empirically known that in E may be correlated to reciprocal of absolute temperature.