Formation of CO32- and HCO3- species without the participation of the framework-bridging oxygen atoms (-O-) upon chemisorption of CO2 in zeolite vertical bar Na-12 vertical bar-A is revealed. The transfer of O and H atoms is very likely to have proceeded via the involvement of residual H2O or -OH groups. A combined study by the solid-state H-1 and C-13 MAS NMR, quantum chemical calculations, and in situ infrared spectroscopy showed that the chemisorption mainly occurred by the formation of HCO3-. However, at a low surface coverage of physisorbed and acidic CO2, a significant fraction of HCO3- was deprotonated and transformed into CO32-. We expect that a similar chemisorption of CO2 would occur for low-silica zeolites and other basic silicates of interest for capture of CO2 from the gas mixtures.