Activity coefficients at infinite dilution gamma(infinity)(1) of 17 polar solutes included linear and branched C-1 to C-5 alcohols, chlorinated methane, acetone, acetonitrile, ethyl acetate, 1,4-dioxane, and cyclohexanone in the ionic liquid 1-butyl-3- methylimidazolium tetrafluoroborate were determined by gas chromatography using the ionic liquid as the stationary phase. The measurements were carried out at temperatures between (303.15 and 343.15) K. From the temperature dependence of the limiting activity coefficients, partial molar excess enthalpies at infinite dilution H-1(E,infinity) of the organic solutes in the ionic liquid have been derived.