Different Li4SiO4 solid solutions containing aluminum (Li4+x(Si1-xAlx)O-4) or vanadium (Li4-x(Si1-xVx)O-4) were prepared by solid state reactions. Samples were characterized by X-ray diffraction and solid state nuclear magnetic resonance. Then, samples were tested as CO2 captors. Characterization results show that both, aluminum and vanadium ions, occupy silicon sites into the Li4SiO4 lattice. Thus, the dissolution of aluminum is compensated by Li1+ interstitials, while the dissolution of vanadium leads to lithium vacancies formation. Finally, the CO2 capture evaluation shows that the aluminum presence into the Li4SiO4 structure highly improves the CO2 chemisorption, and on the contrary, vanadium addition inhibits it. The differences observed between the CO2 chemisorption processes are mainly correlated to the different lithium secondary phases produced in each case and their corresponding diffusion properties.