Proposed is the research and development necessary to demonstrate the feasibility of a vapor refrigeration cycle which is capable of directly and continually cooling areas of the body through the liquid to-gas phase change of freon 114 at the site to be cooled. A pre development laboratory prototype will be built and demonstrated which (a) eliminates the need for a pump to transfer cooling medium to the body, (b) eliminates the buildup of dangerous gas pressures in the vest, (c) eliminates the danger of freezing tissue, (d) operates successfully in high ambient temperatures, (e) provides for continuous high cooling rates on demand so long as it has power, and (f) makes possible the development in phase II of a miniaturized version which will have all the foregoing attributes as well as being smaller and much lighter weight than existing portable devices for auxiliary cooling.