The use of metal oxide absorbents in a portable life support system (PLSS) for regenerative removal of both CO2 and H2O vapor is the focus of an ongoing NASA program. This program addresses the rigorous extravehicular activity (EVA) requirements for Space Station Freedom and future long-duration missions. The concurrent removal of CO2 and H2O vapor can simplify the PLSS by combining the CO2 removal and humidity control functions in one component. A further benefit is that the reversible gas/solid chemical reaction of the removal processes permits a regenerative component that does not vent to space.Recently a preprototype full-scale metal oxide carbon dioxide and humidity remover (MOCHR) and a regeneration module were delivered to NASA Johnson Space Center (JSC). Prior to delivery, preliminary testing of the MOCHR and regeneration module was conducted at AiResearch. The preliminary test results show that CO2 and H2O can regeneratively be removed concurrently in one component at rates and under conditions applicable to the PLSS. Further testing is planned at NASA-JSC to verify the design, to evaluate CO2 and humidity removal, and to determine the operational life of the metal oxide absorbent. This paper discusses the development of the preprototype hardware and the results of preliminary testing conducted to date.