The activity coefficients at infinite dilution for some alkanes, cycloalkanes, alkenes, alkynes and benzene in furfural have been determined by g.l.c. at T = 278.15 K and T = 298.15 K. The volatility of the solvent furfural, although low, was taken into account. The method used is an alternative to the pre-saturation method. The results have been used to predict the potential for furfural as a solvent in separating aromatic compounds from aliphatic compounds and other hydrocarbons using extractive distillation. The excess enthalpies of mixing at infinite dilution have also been calculated. (C) 2004 Elsevier Ltd. All rights reserved.