The Ru-O bond distance of the bridge in cis,cis-[(bpy)(2)(NH3)RuORu(NH3)(bpy)(2)](4+) (2) is 1.8939(15) Angstrom, the Ru-O-Ru angle is 158.2(4)degrees, the N1(ammonia)-Ru-Ru-N1(ammonia) torsional angle is 28.45 degrees, and the distance between the N atoms of the ammines is 4.816 Angstrom. Electrochemical oxidation of 2 in acid gives N-2 and oxidized forms of cis, cis-[(bpy)(2)(H2O)(RuORuIII)-O-III(OH2) (bpy)(2)](4+) (1). The net reaction shown below occurs by reversible, 1-electron oxidation to [(bpy)(2)(NH3)RuORu(NH3)(5)](5+) followed by irreversible 5-electron oxidation and proton loss. At pH 12.2, cis,cis-[(bpy)(2)(NO2)RuORu(NO2) (bpy)(2)(NO2)RuORu(NO2)(bpy)(2)](2+) is formed in 11% yield by a competitive pathway involving capture of an oxidized intermediate by OH-.