Precipitation of lysozyme solubilized in the reverse micelles of sodium bis-(2-ethylhexyl) sulfosuccinate in 2,2,4-trimethylpentane (isooctane) using pressurized CO2 has been studied at 298.2 K. It was found that lysozyme can be precipitated by the dissolved CO2 even at low CO2 pressure. The solubilization propel ties of the reverse micelles can be controlled by simply tuning the pressure of CO2. Using this method, lysozyme can be precipitated completely and lysozyme solid can be obtained. (C) 2001 Elsevier Science B.V. All rights reserved.