A cobalt complex, Co (Ⅱ) complex of his(salicylideneethylene diamine, Cosalen) immobilized to chitosan film was prepared. It was instrumentally characterized by elemental analyses, IR, UV-VIS, XPS and ESR spectroscopy. It was demonstrated that the immobilization of Cosalen was realized through the coordination of the amino group in Chitosan with the Co (Ⅱ) in the CoSalen complex. It binds molecular oxygen reversibly in the solid state through the vacant sixth coordination site.