Methylated poly(vinyl amine) brushes generated on PS-DVB microspheres were demonstrated as excellent macroligands, forming hydrophilic Co(II) chelates capable of reversible molecular oxygen binding. The oxygenation is extremely fast when counteranions of cobalt are replaced with hydroxyl ions. The experiments carried out using oxygen sensor, FT-IR, TGA techniques, and gas volumetric measurements showed that the polymer complexes with either 4/1 or 2/1 [amine]/[Co] ratios form 1:1 molecular oxygen adducts which are stable up to 110-120 degrees C. In order to impart the chain extension effect, poly(vinyl amine-stat-DADMAC) brushes were also generated on the microspheres by using DADMAC as additional comonomer. Fast oxygenation, high oxygen binding capacity (ca. 80 mL/g), and long-term stability of the oxygen adducts make the polymeric complex superior to current systems. The cobalt complex system presented can be considered as a high capacity solid matrix for dissociation and chemical storage of the molecular oxygen from air.