Abstract Amberlite LA-2 (a secondary amine) was studied for its ability to extract propionic acid at different amine concentrations. The extraction of propionic acid by Amberlite LA-2 dissolved in seven single solvents (cyclohexane, 2-octanone, toluene, methyl isobutyl ketone, isooctane, haxane and 1-octanol) was investigated under various amine concentrations at 298.15 K. Using Bizek's approach, two acids: amine complexes , (HO):(R 2 N) and (HO):(R 2 N) 2 , are assumed to exist in the organic phase in case of proton-donating diluents, while the complexes (HO):(R 2 N) and (HO) 2 :(R 2 N) 3 are suggested in the case of non-proton-donating diluents. Important data for design of separation units have been obtained as a result of batch experiments. These data are distribution coefficients ( D ), loading factors ( Z ), extraction efficiency ( E ) and overall extraction constants ( K 11 , K 12 , K 23 ). The maximum removal of glycolic acid is 94.68% with MIBK and 0.93 mol L −1 initial concentration of Amberlite LA-2.