The oxidation of 14 hydrazones with iodine in the presence of base (generally triethylamine) was investigated. The typical reaction products are mixtures of gem-diiodides and vinyl iodides obtained in total yields of 38-85%. The features of the reaction are consistent with a mechanism involving an intermediate iododiazonium salt and/or an iodocarbonium ion. The preparation and purification of hydrazones was investigated.