NASA's planned future missions set stringent demands on the design of the Portable Life Support Systems (PLSS) used to cool the astronaut and provide them with air. Dramatic reductions in weight, decreased reliance on supplies and greater flexibility on the types of missions are all needed. The CO2 and humidity control unit in the existing PLSS design is relatively large, since it has to remove 8 hours worth of CO2. If the sorbent regeneration can be carried out during the extravehicular activity (EVA) with a relatively high regeneration frequency, the size and weight of the sorbent canister can be significantly reduced. TDA Research, Inc. (TDA) proposes to develop a compact, regenerable sorbent-based system to control CO2 and humidity in the space suit ventilation loop. The sorbent can be regenerated using space vacuum during the EVA, eliminating many of the duration-limiting elements in the life support system. In the Phase I project, TDA will develop a suitable sorbent and carry out a preliminary design and engineering assessment of the system to determine whether the concept merits further research and development.