The purpose of this study is to propose a simple cubic equation of state for the prediction of phase equilibria in highly non ideal systems. The NRTL-PR equation of state is based on the association of the Peng−Robinson EoS and the generalized NRTL model developed in the first part of this work. This model, which derives from the lattice two-fluid theory, was specially developed to take account for the differences in size and shape between mixture components. The main advantage of the resulting NRTL-PR equation of state is to yield a simple and predictive model, depending on very few interaction parameters. In addition, it also allows satisfactory predictions of excess enthalpies, liquid−vapor and liquid−liquid equilibria occurring in mixtures formed by very asymmetric compounds, such as hydrocarbons, water, and ethylene glycols.