(60)Co sources ( approximately 37 kBq) in the form of a thin film are widely used in position identification of perforation in offshore oil-well explorations. This paper describes the large-scale preparation of such sources using a radioactive polymer containing (60)Co. (60)Co was extracted into chloroform containing 8-hydroxyquinoline. The chloroform layer was mixed with polymethyl methacrylate (PMMA) polymer. A large film was prepared using the polymer solution containing the complex. The polymer film was then cut into circular sources, mounted on a source holder and supplied to various users.