We have prepared and characterized a Ni complex with an N3S2 ligand set (1) that represents the first isolable synthetic model of the reduced form of the Ni-SOD (SOD = superoxide dismutase) active site featuring all relevant donor functionality in the proper spatial distribution. As revealed by X-ray crystallography, the axial py-N donor of 1 does not bind Ni-II in the solid state or in solution like SOD. Oxidation of 1 provides a disulfide-linked dinuclear species, [{Ni(N3S2)}(2)] (2), which we have isolated and characterized. Moreover, the 1 -> 2 conversion is reversible, much like redox cycling in the enzyme.