When a permanent human outpost is established on the Moon, various methods may be used to reject the heat generated by the base. One proposed concept is the use of a heat pump operating with a vertical, flow-through thermal radiator mounted on a Space Station type habitation module . Since the temperature of the lunar surface varies over the day, the vertical radiator sink temperatures can reach much higher levels than the comfort and even survivability requirements of a habitation module. A high temperature lift heat pump will not only maintain a comfortable habitation module temperature, but will also decrease the size of the radiators needed to reject the waste heat. Thus, the heat pump will also decrease the mass of the entire thermal system.Engineers at the Johnson Space Center (JSC) have tested a High Lift Heat Pump design and are developing the next generation heat pump based on information and experience gained from this testing. The High Lift Heat Pump was designed and built for JSC as a proof-of-concept system to investigate heat rejection to harsh environments such as the lunar surface and other planetary habitats. The High Lift Heat Pump uses a two stage vapor compression cycle to achieve the rejection temperatures needed on the equator during lunar noon. The heat pump also uses off-the-shelf technology and HCFC-123 as the working fluid to achieve the high temperature lift. This paper provides a description of the heat pump design, an overview of the test program, the system performance, results, and lessons learned that will be useful in future heat pump development programs.