Carbon monoxide, CO, is an anthropogenic toxic pollutant and its mixture is easily flammable by heated surfaces and open flames. Thus, developing effective adsorbents with a high uptake capacity to adsorb CO from incomplete burned air and flammable gases containing CO is required. Because nanoporous materials are reported to show high performance as adsorbents, we prepared mesoporous alumina (MA) and used it as the CO adsorbent. MA prepared by the post-hydrolysis method showed pore properties such as a uniform pore size, an interlinked pore system, and a large surface area, as compared to commercial adsorbents (activated carbon, zeolite, and silica powder). Adsorption isotherm test was carried out to evaluate the adsorption performance of the as-prepared MA. In addition, Pd-nanodots were immobilized on the MA to enhance the uptake capacity of CO. MA exhibited six to seven-times higher uptake capacity for CO than commercial adsorbents, and its maximum uptake capacity increased 1.3-3.1 times through Pd-nanodots loading. Although the larger surface area of adsorbents is an important factor for ideal adsorbents, a regular and interlinked pore system of adsorbents was found to be more crucial factor to adsorb CO.