Succinic acid has recently been drawing much interest as a raw material for biodegradable polymer. In this study succinic acid was separated by reactive extraction with tertiary amines dissolved in various diluents. Distribution coefficients were determined as the function of TPA(tripropylamine) concentrations, diluents, and chain length of tertiary amines. The extraction capacity increased with the polarity of diluents, the concentration of TPA in organic phase and the chain length of amines. Furthermore, the coextracted water into the organic phase enhanced the solubility of succinic acid into organic phase.