452The fundamentals and techniques of supercritical fluid extraction (SFE) and retrograde condensation (RC) processes are described. Supercritical (CO2 and other biologically nontoxic supercritical fluids (SCFs) are found to be effective extracting agents of many compounds of interest in biotechnology. It is demonstrated that supercritical solubility calculation methods can be improved through the use of statistical mechanical theories of asymmetric mixtures. Such computation techniques could be successfully applied to improve engineering design. In addition, the effect of mixed supercritical solvents on the solubility of heavy solutes, at different pressures, temperatures, and solvent compositions is studied. The prospects for the commercial application of SFE/RC phenomena in biological processes are discussed and a review of important biotechnological applications of SFE/RC processes is presented.