Methylated poly(vinyl amine) and its copolymer with diallyldimethylammonium chloride (DADMAC) were prepared by polymerization of N-vinyl formamide (NVF) or copolymerization with DADMAC. Acid hydrolysis of the polymers and subsequent methylation yielded corresponding polyamines. Co(II) complexes of the polyamines were demonstrated to be reasonably fast in molecular oxygen binding, when counter anions of cobalt are exchanged with hydroxyl ions. The oxygenation tests performed with oxygen sensor, FT-IR, and gas-volumetric methods revealed that complexes either with 4/1 or with 2/1 [amine]/[Co] ratios give 1:1 molecular oxygen adducts. Fast oxygenation (c.a. 2-4min), high storage capacity, and smooth oxygen releasing within 70-120 degrees C are typical characteristics of the oxygenation-deoxygenation. The system seems to be useful for harvesting and chemical storage of air oxygen.