The activity coefficients at infinite dilution, gamma(infinity)(13) for 32 solutes: alkanes, alken-1-es, alkyn-1-es, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, tert-butyl methyl ether, and water in the ionic liquid 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN] were determined by gas-liquid chromatography at the temperatures from 298.15 K to 368.15 K. The values of the partial molar excess enthalpies at infinite dilution Delta H-1(epsilon,infinity) were calculated from the experimental gamma(infinity)(13) values obtained over the temperature range. The selectivities for the hexane/benzene, cyclohexane/benzene, hexane/thiophene, and other separation problems were calculated from the gamma(infinity)(13) and compared to the other ionic liquids, N-methyl-2-pyrrolidinone, and sulfolane, taken from the recent literature. This work demonstrates that with chosen ionic liquid it is possible to separate different organic compounds with the highest selectivity, ever published. (C) 2009 Elsevier Ltd. All rights reserved.