A database on activity coefficients of organic solutes at infinite dilution in ILs was collected from literature sources. The activity coefficient model with the combinatorial term represented by the Kikic et al. was used as a modification to Flory's equation. The activity coefficients had been used to correlate the solubility parameter of ionic liquids. The obtained solubility parameters of ionic liquids had been further correlated based on a concept of the group contribution method. Through the analysis of the database and the prediction results of selectivities at infinite dilution of xylene isomers, we showed that higher selectivity can be achieved by using ILs as working solvents for separation of xylene isomer mixtures. (C) 2014 Elsevier B.V. All rights reserved.