EDTA-MMA-BA copolymer was prepared by radical polymerization in aqueous solution. EDTA, which chelated cobalt ions (Co2+), at the chain end of copolymer was as an oxyphilic carrier Different cobalt ions contents of chelated copolymer membranes were prepared and shown good oxygen permeability (P-O2=10x10(-9) cc(STP)cm/cm(2) s cmHg (100 barrer)) and highly permselectivity (alpha(O-2/N-2)=10) of oxygen/nitrogen. The separation factor increased with the increasing of Co2+ contents in copolymer membranes. Both the permeation behaviors and the change of pressure were in good agreement with Petropoulos [J.H. Petropoulos, J. Polym. Sci. A2 8 (1970) 1797], Paul and Koros' [D.R. Paul, W.J. Koros, J. Polym. Sci.: Polym. Phys. Ed. 14 (1976) 675] modified dual-mode absorption theory. The relationship between the oxygen or nitrogen permeability and temperature follows the Arrhenius relation. The apparent diffusion activation energies of oxygen and nitrogen were estimated to be 7.4-11.4 and 12 kcal/mol, respectively.