In this work, we report the infinite dilution activity coefficients (gamma(infinity)(1,2)) of 39 to 43 diverse organic solutes dissolved in three 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids (IL) homologues bearing propyl, butyl, and pentyl n-alkyl side chains, respectively, as determined by inverse gas chromatography at temperatures from 323 K to 343 K The organic solutes include various (cyclo)alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, ethers, nitroalkanes, and ketones. The measured retention data were further transformed to gas-to-IL and water-to-IL partition coefficients using established thermodynamic approaches based upon the corresponding gas-to-water partition coefficients of the test solutes. Both sets of partition coefficients were interpreted with a modified form of the basic Abraham general solvation parameter model. The mathematical correlations obtained by regression analysis back calculated the observed gas-to-IL and water-to-IL partition coefficient data to within average standard deviations of 0.104 and 0.136 log units, respectively.