The group contribution equation of state (GC-EoS) is used to describe the phase behavior of gas + ionic liquid mixtures. With this equation, by application of the group contribution concept, if the parameters of the characteristic functional group of a family of ionic liquids are calculated using experimental data of a reduced number of ionic liquids of the family, then the phase behavior of all ionic liquids of the same family can be predicted. With this work, the parameter table of the GC-EoS is extended to systems that are comprised of an ionic liquid of the methylimidazolium bis[(trifluoromethyL)sulfonyl]limide family [-mim][Tf2N] and a gas (H-2, CO, C2H4, O-2, SO2, CH3OH, N2O, or Xe). Furthermore, a compilation of all GC-EoS parameters for gas + ionic liquid systems currently available in the literature is presented.