Etectrocatalytic water oxidation occurs through the use of the phosphonate-derivatized single-site catalyst [Ru(Mebimpy)(4,4'-((HO)(2)OPCH2)(2)bpy)(OH2)](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2'-bipyridine] at pH 1 and 5 on fluorine-doped SnO2 or Sn(IV)-doped In2O3 electrodes or on nanocrystalline TiO2. The surface-bound catalyst appears to retain the water oxidation mechanism found for [Ru(tpy)(bpm)(OH2)](2+) and [Ru(tpy)(bpz)(OH2)](2+) (tpy = 2,2':6',2 ''-terpyridine; bpm = 2,2'-bipyrimidine; bpz = 2,2'-bipyrazine) in solution and acts as a surface electrocatalyst for sustained water oxidation.