Micellar aggregates are known to be useful for the selective isolation of biologically active materials such as amino acids, proteins, and enzymes from crude mixtures sparsely dispersed in water. In this study, the effects of pH, salt type and its concentration on the solubilization of $alpha$-chymotrypsin into the organic micellar phase, which consisted of AOT (sodium 야(2-ethylhexy)sulfosuccinate) and iso-octane, were comprehensively examined. It was found that maximum extraction efficiency was attained at a pH below the isoelectric point of $alpha$-chymotrypsin; at pH=5.0 for NaCl and KCl, and at pH=7.0 for $CaCl_2$and $MgCl_2$. In order to avoid complications stemming from the precipitationof protein at low pH interfaces, the protein concentrations in the organic and aqueous phases were directly measured. The size of the micelle water pool was estimated by measuring the molar ratio of the surfactant to the water, W(sub)o. The resulting values of W(sub)o were nearly constant at 30 and 19 for NaCl and KCl, respectively, and were independent of pH. The addition of 1:2 salts like $MgCl_2$and $CaCl_2$ led to much lower, but a constant value of, W(sub)o than the 1:1 salts.