Recently, technique of CO₂ separation from exhaust mixture gases is desired as one of countermeasures against the environmental problems. Material used for the separation technique must be compact and can absorb CO₂ quickly. Moreover it must be used repeatedly. From these requirements, Li-Metal oxides (typical example Li4SiO₄) are regarded as a novel solid CO₂ absorbent. Previously, we have investigated temperature dependence of CO₂ absorption behavior of Li4SiO₄, and studied on a method to measure reaction rate of CO₂ absorption reaction of Li4SiO₄ by means of a TG and DTA apparatus with an IR Gold image furnace. Furthermore, we have successfully synthesized new Li-Metal oxides Li4TiO₄ and Li2CuO₂, and measured their CO₂ absorption behavior by means of the apparatus and the method. For three kinds of powdered samples (Li4SiO₄, Li4TiO₄, and Li2CuO₂), CO₂ absorption defined by "mass increase per sample gram" were measured by the apparatus when the samples were heated with the heating rate of 5 ℃ min^－1. up to 1000 ℃ in 100 vol% CO₂ atmosphere. It was found that the maximum CO₂ absorption was measured 36.7 mass%, 42.1 mass%, and 40.2 mass%, respectively for Li4SiO₄, Li4TiO₄,and Li2CuO₂. The maximum CO₂ absorption of the Li4TiO₄ sample was larger than those of Li4SiO₄ and Li2CuO₂. In order to measure rate constant k of CO₂ absorption reaction for three samples, mass increase of the samples was measured with time at a measurement temperature in 100 vol% CO₂ atmosphere. From the results, it was found that, in temperature region of 680 ℃～700 ℃, the rate constant k of the CO₂ absorption for Li2CuO₂ were almost three times larger than that of Li4SiO₄ sample.