Cryogenics, the science of extremely cold temperatures, has been a part of the NBS/NIST research portfolio ever since NBS purchased the hydrogen liquefier exhibited at the 1904 St. Louis World’s Fair. This NIST History Lecture begins with some of the early NBS cryogenic “firsts” on the D.C. campus and brings in significant events on the international scene that led President Truman to announce in 1950 that the U.S. would develop the thermonuclear (hydrogen) bomb. Dr. Radebaugh will cover the fascinating story behind the selection of NBS and Boulder to assist in this crash R&D program involving cryogenics. The first thermonuclear test in 1952 was very successful, but by 1954 Los Alamos scientist perfected a “dry” version using lithium deuteride that eliminated the need for cryogenics in H-bombs. Weapons funding for the Cryogenics Division quickly evaporated, but ensuing NASA space missions and classified work for the Air Force kept the Cryogenics Division active for years. In this History Lecture we will learn about the many national needs met by the research activities of the Cryogenics Division between 1952 up to its split in 1978. The last part of the presentation will follow the research and impact of the major pieces of the split.