The cobalt (II)-exchanged zeolite A (NaCoA) was prepared by cation exchange process with zeolite A (NaA) and Co(NO(3))(2) in aqueous solution. A static volumetric system was employed to evaluate the N(2) and O(2) adsorption properties of NaCoA at 298 K. It was found that the N(2) adsorption capacity of NaCoA increased rapidly with the rising pressure, and the adsorption isotherm of N(2) became nonlinear in low pressure region. The O(2) adsorption capacity of NaCoA increased slightly with pressure. The introduction of Co(2+) into the NaA enhanced the N(2) adsorption capacity and N(2)/O(2) selectivity, which could be contributed to the pi-complexation between N(2) and Co(2+). This strong interaction brought about a series of high value for Henry's constant, Langmuir constant, adsorption selectivity and adsorption capacity of N(2) in NaCoA. Infrared spectra were also carried out to illustrate that the N(2) were bonding with Co(2+). (C) 2010 Elsevier Ltd. All rights reserved.