The current study proposes a scheme for generalizing parameters of SAFT + Cubic EoS (GSAFT + Cubic) for predicting and correlating thermodynamic properties of heavy (18 and more carbon atoms) organic substances and of ionic liquids. The accuracy of the proposed approach might usually be compared with the multi-parameter empirical Tait equation. However, unlike the latter one, it has a predictive character. In the cases of the substances included in the databanks such as DIPPR, GSAFT + Cubic requires input of a single experimental density datum point. In the cases of complex fluids, such as the heavy oils, the ionic liquids or the ester lubricants, the proposed approach requires input of two experimental points of density and estimation of the ideal gas heat capacity for predicting various auxiliary properties in wide PVT range. A major advantage of GSAFr + Cubic over the empirical correlations is its applicability for estimating phase equilibria and other thermodynamic properties of mixtures while using the one-fluid approach. In particular, it has been demonstrated that GSAFT + Cubic yields accurate predictions of the available VLE and LLE data of mixtures of the heavy n-alkanes and the ionic liquids. (C) 2012 Elsevier B.V. All rights reserved.