Lithium cuprate (Li2CuO2) was prepared by solid state reaction, using different quantities of lithium excess, which produced nonstoichiometric ceramics, Li2+xCuO2+x/2. These ceramics were characterized by X-ray diffraction, transmission and scanning electron microscopies, solid state nuclear magnetic resonance, and atomic absorption. The results obtained showed that lithium excess is located mainly into the Li2CuO2 interlayers forming nanoparticles of a different phase, perhaps lithium oxide. Additionally, the lithium excess produced morphological changed at a micrometric and nanometric levels. As lithium excess increased, the particle size increased as well and it formed some kind of filament-like structures. It was explained in terms sintering, due to the high mobility of lithium atoms. On the other hand, all these ceramics were tested as CO2 captors, presenting encouraging properties through a chemisorption process. As expected, the CO2 absorption increased as a function of total lithium contained into the ceramics. Finally, it was performed a kinetic analysis of the CO2 absorption.