Reductive electropolymerization of [Ru^II(PhTpy)(5,5′-dvbpy)(Cl)](PF₆) and [Ru^II(PhTpy)(5,5′-dvbpy)(MeCN)](PF₆)₂ (PhTpy is 4′-phenyl-2,2′:6′,2″-terpyridine; 5,5′-dvbpy is 5,5′-divinyl-2,2′-bipyridine) on glassy carbon electrodes gives well-defined films of poly{[Ru^II(PhTpy)(5,5′-dvbpy)(Cl)](PF₆)} (poly-1) or poly{[Ru^II(PhTpy)(5,5′-dvbpy)(MeCN)](PF₆)₂} (poly-2). Oxidative cycling of poly-2 with added NO₃^– results in the replacement of coordinated MeCN by NO₃^– to give poly{[Ru^II(PhTpy)(5,5′-dvbpy)(NO₃)]⁺}, and with 0.1 M HClO₄, replacement by H₂O occurs to give poly{[Ru^II(PhTpy)(5,5′-dvbpy)(OH₂)]²⁺} (poly-OH₂). Although analogous aqua complexes (e.g., [Ru(tpy)(bpy)(OH₂)]²⁺) undergo rapid loss of H₂O to MeCN in solution, poly-OH₂ and poly-OH₂⁺ are substitutionally inert in MeCN. The substitution chemistry is reversible, with reductive scans of poly-1 or poly-OH₂ in MeCN resulting in poly-2, although with some loss of Faradaic response.