Synthetic peptides are widely used as hormones, vaccines andother potent new pharmaceuticals. Methods of synthesis differ radically whether solution phase or solid phase chemistry is used. This sbir proposal deals with solid phase synthesis, while a separate sbir proposal is being submitted on solution phase chemistry. Both aim at improvement of the synthetic processes through the use of supercritical co2 (sc-co2) as the reaction medium. While the unique properties of supercritical fluids (scf) have been known for a long time, intensive research in scf usage is only of recent vintage. Most applications of scf are in extractive processes, rather than chemical synthesis,and none has yet been tried for peptide synthesis. Sc-co2 is particularly interesting because of its low critical temperature, 31.12c, solvent which could be generated in space or on moon from locally available resources. Thus, a variety of scf processes may become of importance to nasa. We wish to study the synthesis of peptides because of their very high value per unit weight, great economic and socio-medical value and the possibility of achieving significant improvement of the process in microgravity.