This work reports activity coefficients at infinite dilution of 31 organic compounds in 1-hexadecyl-3-methylimidazolium tetrafluoroborate [C16MIM][BF4] determined using inverse gas chromatography. The measurements were carried out at temperatures (323.15, 333.15, and 343.15) K. Flory-Huggins interaction parameter and solubility parameter were calculated from an experimental retention data. (c) 2007 Elsevier Ltd. All rights reserved.