Fractionation of a mixture of oleic acid/squalene using room temperature ionic liquids as the extracting agent has been investigated for a range of imidazolium and phosphonium based ionic liquids. The partition coefficient of oleic acid to the ionic liquid phase varied from 0.85 for [C-2][NTf2] to 2.96 for [EMIM][MDEGSO(4)]. It was observed that the fractionation of the oil mixture could be tuned by appropriately choosing the combination of the anion and cation type. This effect could be explained by the change in the polarity of the ionic liquid. (C) 2010 Elsevier B.V. All rights reserved.