•Nanocrystalline Li2SiO3 powders were synthesized via microwave-assisted hydrothermal method.•Pure Li2SiO3 phase was obtained using short reaction time at low temperature.•Li2SiO3 particles exhibited hollow sphere morphologies and high specific surface area.•Water vapor and CO2 capture properties were evaluated by thermogravimetric analysis.•Exhibited properties suggested potential applications of Li2SiO3 as catalyst and CO2 sorbents. A series of lithium metasilicate (Li2SiO3) powder materials has been successfully synthesized by the microwave-assisted hydrothermal route using lithium hydroxide and tetraethyl-orthosilicate-derived sol precursors. Ceramic powders were obtained under hydrothermal conditions of autogenous pressure in the presence of a nonionic surfactant. The production of pure and well-crystallized Li2SiO3 using very short reaction times at low temperatures was shown by X-ray diffraction, scanning electron microscopy, and N2 adsorption-desorption analyses. Synthesized Li2SiO3 particles were nanocrystalline and exhibited different morphologies and specific surface areas depending on the synthesis conditions. Additionally, the capability of selected Li2SiO3 samples to absorb H2O and CO2 was evaluated via thermogravimetric analyses by varying the temperature, carrier gas, and water vapor concentration. Li2SiO3 particles exhibited interesting textural and morphological characteristics that make them suitable for use as a CO2 absorbent and which suggest that they also have the potential to be used in other applications.