The antioxidant properties of a number of water-soluble diorganyl tellurides have been investigated. These organotellurium compounds efficiently protect against peroxynitrite-mediated oxidation of dihydrorhodamine 123, hydroxylation of benzoate, and nitration of 4-hydroxyphenyl acetate. The peroxidation of the zinc storage protein, metallothionein, by tert-butyl hydroperoxide is also catalyzed by the water-soluble organotellurium compounds. As compared to selenium-containing compounds (e.g., ebselen and selenocystamine), some of the tellurides that were tested ¿e.g., 3-[4-(N,N-dimethylamino)benzenetellurenyl]propanesulfonic acid, sodium salt¿ exhibit a significantly higher reactivity in these assays, making them some of the most effective compounds tested thus far. The catalysis of destruction of zinc-sulfur clusters by water-soluble organotellurium compounds could have implications for the bioavailability of zinc in vivo. These compounds might be lead compounds for the development of a new class of water-soluble, tellurium-based antioxidant and zinc-releasing drugs.