Adsorption and desorption characteristics of carbon dioxide on sodium oxide impregnated alumina particles are investigated using a small-scale packed-bed reactor (PBR) at different feed concentrations (5-14%), different bed temperatures (25-300 degrees C), and in the presence or absence of steam. The adsorption capacities are calculated from the breakthrough curves measured in the PBR. The adsorption capacities at different temperatures suggest that a physisorption mechanism may dominate at low temperatures, while a chemisorption mechanism dominates at high temperatures. The presence of steam enhances CO2 adsorption. Implications for adsorption-enhanced processes are discussed.