The effects of pH, ionic strength,and amino acid and surfactant concentrations on the reverse micellar extraction of aspartic acid, glutamic acid, and threonine using dioctyldimethylammonium chloride (DODMAC), were determined. The concentrations of the ionic species in the aqueous phase were measured, and the corresponding concentrations inside the reverse micelles were obtained by material balances and the condition of electrical neutrality. The results show that the amino acids were mainly extracted through an ion exchange mechanism. The net charge of an amino acid, the competition among anions, the dissociation equilibrium of DODMAC, and the water uptake in the reverse micelles are important factors which dominate the amino acid extraction.