A novel oxalate-bridged binuclear ruthenium(III) complex, [{Ru(acac)(2)}(2)(mu-ox)] (acac(-) = acetylacetonate and ox(2-) = oxalate), has been prepared via self-dimerization of K[Ru(acac)2(OX)l in aqueous solutions containing ferric salts as catalyst. The Ru-2 III,II mixed-valence species generated electrochemically with K-c = 10(5.0) for the comproportionation constant exhibits a weak intervalence charge transfer (IVCT) band at 1430 nm. The IR spectra from spectroelectrochemistry indicate a partially localized mixed-valence state (Class II-III behavior).