We synthesized nanoporous CO-selective adsorbent composed of CuCl supported on bayerite. Before supporting the CuCl, the bayerite chemical was calcined at 623 K to increase the surface area to 469 m(2) g(-1). The CuCl was highly dispersed on the activated bayerite via a thermal monolayer dispersion process. The highest CO adsorption capacity was achieved at an optimal temperature of 573 K and CuCl content of 30 wt%. Thus synthesized adsorbent exhibited a high CO adsorption capacity of 48.5 cm(3) g(-1) at 293 K, but a very low CO2 adsorption capacity (2.89 cm(3) g(-1)), resulting in CO/CO2 separation factor of 16.8. When the CuCl content increased to 36 wt%, the adsorbent exhibited much higher separation factor (35.5), although the CO adsorption capacity was somewhat smaller (41.6 cm(3) g(-1)). The CO adsorption capacity and CO/CO2 selectivity of this adsorbent are larger than those of our previous CuCl/boehmite adsorbent showing CO adsorption of 34 cm(3) g(-1) and a CO/CO2 separation factor of 12.4. The present adsorbent also shows very high selectivity for CO over H-2, N-2, and CH4. Therefore, this adsorbent is expected to show excellent CO separation performance for various industrial processes such as steam-reforming and steel-making which involve CO, CO2, H-2, N-2, and CH4.