The phosphonated ruthenium complex, [RU(tPY-PO3H2)(OH2)(3)](2+) (1) (tPY-PO3H2 = 4 '-phosphonato-2,2 ':6 ',2 '' terpyridine), was synthesized and attached to glass vertical bar ITO or glass vertical bar ITO vertical bar TiO2 electrodes. After attachment to the metal oxide surface through the phosphonate linkage, 1 can be oxidized (either chemically or electrochemically) to the reactive Ru(VI)-dioxo complex, glass vertical bar ITO vertical bar[((HO)(2)OP)tpy) Ru-VI(O)(2)(OH2)](2+) which remains attached to the surface. The attached Ru(VI) complex reacts with benzyl alcohol through mechanisms similar to those proposed for the solution analog. More specifically, Ru(VI) is reduced in a stepwise fashion to Ru(IV) and then finally to Ru(II). The reduction of Ru(VI) is accompanied by a rate-limiting insertion to the C-H bond of benzyl alcohol, followed by solvolysis of the aldehyde hydrate. In addition, the surface-bound Ru(VI) acts as an electrooxidation catalyst which carries out similar to 130 (2e(-)) turnovers before deactivation.