Cholesterol metabolism has been recently linked to cancer, highlighting the importance of the characterization of new metabolic pathways in the sterol series. One of these pathways is centered on cholesterol-5,6-epoxides (5,6-ECs). 5,6-ECs can either generate dendrogenin A, a tumor suppressor present in healthy mammalian tissues, or the carcinogenic cholestane-3 beta,5 alpha,6 beta-triol (CT) and its putative metabolite 6-oxo-cholestan-3 beta,5 alpha-diol (OCDO) in tumor cells. We are currently investigating the identification of the enzyme involved in OCDO biosynthesis, which would be highly facilitated by the use of commercially unavailable [C-14]-cholestane-3 beta,5 alpha,6 beta-triol and [C-14]-6-oxo-cholestan-3 beta,5 alpha-diol. In the present study we report the one-step synthesis of [C-14]-cholestane-3 beta,5 alpha,6 beta-triol and [C-14]-6-oxo-cholestan-3 beta,5 alpha-diol by oxidation of [C-14]-cholesterol with iodide metaperiodate (HIO4). (C) 2014 Elsevier Inc. All rights reserved.