Carbon dioxide (CO 2) is a representative greenhouse gas causing global warming, and adsorption becomes a promising technology among many separation methods to capture CO 2. Inexpensive adsorbents with sufficient CO 2 adsorption uptake for low temperature have been widely developed, but their CO 2 adsorption ability is seriously impaired at high temperature. Thus, it is important to develop CO 2 sorbents for high temperature. Hydrotalcite (HTC), which has been known as an inorganic compound of Mg-Al layered double hydroxide, has many advantages of stable CO 2 sorption, fast sorption kinetics, and easy regeneration over other high temperature CO 2 sorbents. However CO 2 sorption uptake of pristine HTC is not high enough for practical use, thus CO 2 sorption uptake of HTC is usually enhanced by impregnation with alkali metals. So far, most enhancement of CO 2 sorption on HTC focused on using potassium carbonate as an impregnation agent. Other alkali metals such as Li, Na, Rb, and Cs were not systematically investigated. In this study, HTC was impregnated with various alkali metals in order to enhance the CO 2 sorption uptake and continuous sorption/desorption test was executed for the comparison of CO 2 sorption kinetics and stability of sorbents. Thermogravimetric analysis was used to measure CO 2 sorption uptake and the results revealed that CO 2 sorption uptake on HTC by impregnated with alkali metal was increased in the order of Na<Cs<K<Rb<Li. Also, the analyses based on N 2 adsorption, X-ray diffraction, scanning electron microscopy and infrared spectroscopy were carried out to elucidate the characteristics of sorbents and the mechanism of CO 2 sorption.