Activity coefficients at infinite dilution (gamma(infinity)(1,2)) for diverse probe solutes in three homologous 1-(4-sulfobutyl)-3-methylimidazolium based ionic liquids were measured by inverse gas chromatography at temperatures from 323 to 343 K. Accordingly, this family of ionic liquid can be ranked according to their interaction with organic compounds as follows: [HSO4] << [OTf] << [N(Tf)(2)]. The retention data were further converted to gas-to-IL and analyzed using the Abraham solvation parameter model. The LSER treatment indicates that the most dominant interaction constants for this family of ILs are strong dipolarity, hydrogen bond basicity and acidity. Then, the ChelpG atomic charges on the cation and the anions obtained by ab initio calculations are used to explain the interactions between methanol, thiophene and benzene and the anions or the cation. (C) 2014 Elsevier B.V. All rights reserved.