In this article, we describe assays carried out to determine the suitability of 13 ionic liquids based on 1-n-alkyl-3-methylimidazolium and n-alkylpyridinium cations and a wide range of anions (hexafluorophophate, bis{(trifluoromethyl)sulfonyl}imide, tetrafluoroborate, methylsulfate, 2(2-methoxyethoxy)ethylsulfate, ethylsulfate, n-octylsulfate, dicyanamide, nitrate, tetrafluoroborate and chloride) to carry out the selective separation of the organic compounds involved in a transesterification reaction (butyl butyrate, vinyl butyrate, 1-butanol, and butyric acid) from hexane solutions. The assayed ionic liquids were shown to be suitable solvents for the selective separation of the target compounds, the extraction process being controlled by the hydrophobicity of the compounds. The anion composition of the ionic liquid was seen to strongly influence the average extraction ratio, the highest value being reached with the chloride-based ionic liquid. As regards the cation composition of the ionic liquids, it was seen that the average distribution ratio increased with decreasing length of alkyl chain. (C) 2010 American Institute of Chemical Engineers AIChE J, 56: 1213-1217, 2010