Bis(μ-hydroxo)dicopper(II,II) bearing a naphthyridine-based ligand has been synthesized and characterized in the solid state and solution. Cyclic voltammetry at room temperature displays a reversible redox system that corresponds to the monoelectronic oxidation of the complex. Spectroscopic and time-resolved spectroelectrochemical data coupled to theoretical results support the formation of a charge-localized mixed-valent Cu(II,III)2 species.