Activity coefficients at infinite dilution gamma(infinity) of organic compounds in the ionic liquid (IL) trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide were determined using inverse gas chromatography at three temperatures, T = (302.45, 322.35, and 342.45) K. Linear free energy relationship (LFER) correlations have been obtained for describing the gas-to-IL and water-to-IL partition coefficients.