Infinite dilution thermodynamic properties of organic solutes dissolved in four bis(sulfonyl)imide ionic liquids namely 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide, 1-ethyl-1-methylimidazolium bis(fluorosulfonyl)imide and 1-methyl-1-propylpiperidinium bis(fluorosulfonyl)imide were measured in a large range of temperature using inverse gas chromatography. The characterization of ILs using the Abraham solvation model indicates that the cation has an impact on the polarizability and on the acidity of the solvent. The derived Abraham model correlations rigorously describe the experimental partition coefficient data to within 0.09 (or fewer) log units. In addition, the activity coefficient at infinite dilution of organic solutes in these ILs was predicted using the conductor-like screening model for real solvents (COSMO-RS). It was found that COSMO-RS give a reasonable representation of experimental data. Then, selectivity and capacity at infinity dilution have been determined for the separation problems (thiophene/water), (benzene/water), (acetone/water), (1-butanol/water), (acetonitrile/water) and (pyridine/water) at 323.15 K.