The effects of pH, ionic strength, co-ion and counterion of the surfactant, alcohol concentration, and nature of the solvent on the reverse micellar extraction of albumin, alpha-chymotrypsin, and lysozyme, using dioctyldimethyl ammonium chloride (DODMAC), were determined. The nature of the solvent or the concentration of the alcohol had no significant effect on extraction. Extraction increased with pH and decreased with salt concentration. A broader range of pH at which proteins can be extracted was obtained with DODMAC compared with bis-2-(ethylhexyl) sulfosuccinate (AOT) and trioctylmethyl ammonium chloride (TOMAC). Negatively charged proteins are extracted from the aqueous phase by exchanging with the Cl- counterion of DODMAC at the reverse micellar interface. The presence of counterions different from chloride in the system, which are introduced through the addition of a salt, has a significant effect on extraction. The highest extraction was obtained in the presence of F- and the lowest in the presence of Br-. The added counterions exchange with the chloride of the surfactant at the reverse micellar interface, thereby changing the nature of the surfactant. In turn, this change in the nature of the surfactant alters the extraction of negatively charged proteins.