A chloramine oxidizing resin has been prepared using nylon-6 as monomeric unit and by the method of substituting hydrogen by active chlorine (Cl+) in hypochlorous acid. The synthesis
oxidizing characteristics and applications in iodine-labelled Pharmaceuticals of the resin are described. A labelling rate of 96% has been obtained for labelled 125I-iodocho-lesterol using this resin.