By using the phase-transfer method, bovine serum albumin(BSA) was solubilized into a reverse micellar phase consisting of sodium bis(2-ethylhexyl) sulfosuccinate(AOT) and isooctane. In order to recover the solubilized protein, the laden organic phase was brought into contact with an excess aqueous phase under a prescribed condition. Of particular interest in this study were the effects of pH and the added salt type and concentration on the forward and backward extraction efficiency. When salt containing univalent or divalent cations such as KCl, NaCl, MgCl2, or CaCl2 were added to the aqueous phase at a concentration of 0.1 M, maximum forward extraction efficiency was achieved at a pH ranging from 5 to 7, depending on the added salt type. Increasing the salt concentration up to 1 M led to an enhanced forward extraction efficiency for CaCl2 and NaCl, while the addition of MgCl2 beyond 0.1 M showed an anomalous trend. Further, it was noteworthy that to a large extent the protein precipitated in the interface between the organic and aqueous phases at lower pHs and lower salt concentrations. The size of the reverse micelle water pool was estimated by measuring the molar ratio of the surfactant to the water, W0. Independently of pH in the aqueous phase, the resulting value of W0 was almost constant, eg., 20 for MgCl2. However, the value of W0 decreased with increase of the salt concentration in the cases of KCl and CaCl2. It was also shown that the backward extraction efficiency of the protein increased with pH and salt concentration in the excess aqueous phase. The higher the salt concentration in the excess aqueous phase, the smaller the value of W0 in the organic phase.