Lithium metazirconate with and without potassium were synthesized by solid-state reaction. Different water vapor sorption experiments were performed in the presence and absence of CO 2 to elucidate the different physicochemical processes produced. In the absence of CO 2 , initial results showed that potassium addition enhances significantly the water sorption on the Li 2 ZrO 3 ceramic. Then, it was shown that water vapor is trapped by two different mechanisms on Li 2 ZrO 3 , adsorption and absorption. When CO 2 was added to water vapor flow the Li 2 ZrO 3 reactivity increased significantly. On the basis of these results, a possible K-Li 2 ZrO 3 -H 2 O-CO 2 reaction mechanism was proposed; as a first step Li 2 ZrO 3 and H 2 O must react producing some Li-OH and Zr-OH species. Then, CO 2 must react with hydroxyl species (mainly Li-OH), producing lithium carbonate. Finally, the presence of this new specie must favor a higher water adsorption.