The aim of this study is to investigate the extraction of succinic acid from aqueous solutions by different organic solutions containing Amberlite LA-2, a secondary amine mixture. Extraction equilibria of succinic acid in the solution of Amberlite LA-2 in seven individual diluents at a temperature of 298.15 K have been measured. Using Bizek's approach, two acid-amine complexes, (HO)center dot(R(2)N) and (HO)center dot(R(2)N)(2), are assumed to exist in the organic phase in the case of proton-donating diluents, while the complexes (HO)center dot(R(2)N) and (HO)(2)center dot(R(2)N)(3) are suggested in the case of nonproton-donating diluents. Important data for the design of separation units have been obtained as a result of batch experiments. These data are distribution coefficients (D), loading factors (Z), extraction efficiencies (E), and overall extraction constants (K(11), K(12), and K(23)).