The alpha- and beta-Li5AlO4 polymorphs were synthesized using a solid-state reaction. The polymorphs were then characterized by X-ray diffraction (XRD), X-ray thermodiffraction (XRTD), and N-2 adsorption. To determine the CO2 chemisorption capacity, the lithium aluminate polymorphs were analyzed thermogravimetrically in the presence of a CO2 flux. In addition, a cyclability study was performed on these ceramic materials. Although the results appear very similar for the two phases, alpha-Li5AlO4 exhibits a better CO2 chemisorption performance. The cyclic performance tests indicate that both materials exhibit a gradually reduced chemisorption capacity after multicycle processes. However, even after many cycles, the chemisorption capacity is considerably high in comparison to other lithium ceramics tested as CO2 absorbents.