Reverse micelles are an effective way to separate and purify proteins by solvent extraction. Optimization of the process requires knowledge of the interfacial mass-transfer rates. In this study, individual mass-transfer coefficients were determined in a cylindrical stirred diffusion cell for the transfer of lysozyme between aqueous 0.1 M KCl solutions containing sucrose or starch, and i-octane containing AOT surfactant. Forward extraction rates were correlated well by the equation, Sh(1) = 0.558Re(1)(0.554)Sc(1)(0.205). Of particular novelty was the measurement of extraction kinetics in the presence of varying concentrations of sucrose and starch. Individual mass-transfer coefficients increased with sucrose concentration, by contrast, the converse was observed for starch. The influence of sucrose and kinetics of the extraction process are discussed.