In this study malic acid were extracted from aqueous solution by different solvents with and without trioctylamine (TOA). The TOA was dissolved in five different esters (dimethyl phthalate, dimethyl adipate, dimethyl succinate, dimethyl glutarate. and diethyl carbonate), five different alcohols (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, and decan-1-ol) and two different ketones (diisobutyl ketone (DIBK) and methyl isobutyl ketone (MIBK)). The results are reported as distribution coefficients (K-D), loading factors (T-T), stoichiometric loading factor (T-S), separation factor (S-f) and extraction efficiency (E). The most effective solvent was determined as isoamyl alcohol with a distribution value coefficient of 17.811. The maximum values of equilibrium complexation constants in isoamyl alcohol for (acid:amine) (1:1) K-11 and (2:1) K-21 were 9.9 and 225.6, respectively. A linear solvation energy relationship (LSER) was accurately regressed to the experimental distribution coefficients. (C) 2009 Elsevier B.V. All rights reserved.