SURSORB PACO-2 is an alkali impregnated adsorbent. It has been an attractive choice for space flight due to its high capacity for carbon dioxide capture (CO2). Rebreather-type personal protective equipment requires efficient removal of CO2 from the air that the user exhales. The required operating conditions of low CO2 partial pressure, low temperature, and water saturation create a challenging environment for developing high-capacity CO2 adsorbents.