Solid soda lime sorbents are promising materials for CO2 removal in closed-circuit breathing systems. In this study, the soda lime sorbent Drägersorb 800+ has been tested in a fixed bed reactor. The changes in composition, structure, and texture of the sorbent occurring in the process of CO2 sorption have been studied using thermogravimetry, X-ray diffraction analysis, nitrogen adsorption (BET), mercury porosimetry and scanning electron microscopy methods. A non-stationary model has been developed for simulating CO2 chemisorption in the fixed bed. The results of the simulation have been found to be in a good agreement with the experimental data.