In order to enhance the selective adsorption of CO2, the surface of granular activated carbon (GAC) was modified by an ammonia solution. Ammonia in an aqueous phase could be decomposed into NH4+, OH- and other N-containing elements. The present work attempted to impregnate some basic functional groups leading to chemisorption of the activated carbon surface. While the addition of N-groups reduced the specific surface area from 2071.4 m2/g to about 1300-1400 m2/g, the adsorption capacity for CO2 increased to a certain degree, and the best amination could be achieved with the reaction at 100℃ for 12 hours. The enhanced adsorption capacity could be obtained by formation of nitrogen functionalities such as amine, pyrrolic groups and pyridine oxides which were verified by XPS analysis. Keywords : CO2, adsorption, activated carbon, ammonia solution, XPS