Liquid-liquid equilibrium (LLE) data for binary mixtures {benzene (1) + ionic liquid (2)) were measured at atmospheric pressure from 293.15 K to 333.15 K. The ionic liquids (Ws) studied were 1-ethyl- and 1-hexyl-3-methylimidazoli um bis( trifluoromethylsulfonyl)imide, EMim][NTf2] and [ HMirn][NTf2]). Furthermore, the group contribution equation of state (GC-EoS) was applied to model the phase behavior of mixtures of hydrocarbons with different members of the homologous family 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [chi-Mim][NTf2]. New pure group parameters for the ionic liquid functional group (MimNTf2) and interaction parameters between this group and the paraffin (CH3, CH2) and aromatic (ACH) groups are reported. The GC-EOS extended with the new parameters was applied to predict LLE and VLE of binary mixtures {benzene + chi-MimNTf(2)} and LLE of ternary systems {n-hexane + benzene + [chi-Mim][NTf2]}}. The results show that the GC-EOS is capable of predicting the phase behavior of this kind of mixtures with reasonable accuracy. (C) 2013 Elsevier B.V. All rights reserved.