[en] Carbon-14 labeled Kanechlors were synthesized in high radiochemical purity. ''Kanechlors'' commercially available polychlorinated biphenyls from Kanegafuchi chemical Industry Co. Ltd., are classified into six types. In order to establish a synthetic method for each type of Carbon-14 labeled Kanechlor, the following experiments were carried out. 1) Distribution patterns and molecular formula of the components of Kanechlors were analyzed with gas chromatography and mass spectrometry. 2) A mixture of chlorobiphenyl isomers was synthesized by direct chlorination of ¹⁴C-Biphenyl with chlorine gas in the presence of ferric chloride. 3) The structure of major components of the Carbon-14 labeled products was identified by comparing the retention times of products with those of Kanechlors of known structure. 4) Optimum reaction condition were studied to prepare Carbon-14 labeled polychlorinated biphenyls with the same composition as Kanechlors KC-300, KC-400, KC-500 and KC-600. (author)