Liquid-liquid equilibrium data were correlated with three mixing rules that incorporate excess Gibbs energy model into a equation of state : Wong-Sandler, Heidemann-Kokal and MHV2 methods. The Soave equation of state is employed to several binary mixtures, coupled with NRTL, UNIQUAC and UNIFAC models for excess Gibbs free energy. The best results for binary mixtures were obtained with NRTL and Wong-Sandler, then this combination was used to predict the ternary liquid-liquid equilibria.