The activity coefficients at infinite dilution, gamma(infinity)(i), of 22 organic solutes in the ionic liquid ethyl(2-hydroxyethyl)dimethyl-ammonium diethylphosphate have been determined using gas-liquid chromatography at the temperatures ranging from 323.15 to 363.15 K. The partial molar excess enthalpies at infinite dilution, H-i(E,infinity) of the solutes in the ionic liquid were calculated from the temperature dependence of the experimental gamma(infinity)(i) values. The selectivity for the hexane/benzene and cyclohexane/benzene separation problems were also derived from gamma(infinity)(i) and compared to the literature values for other ionic liquids and N-methyl-2-pyrrolidone. (c) 2012 Elsevier B.V. All rights reserved.