P, Si, Ge, B) and a monovacant Dawson derivative anion P2W1706i10-were adopted as the ligand for cerium(III). The formation of the complexes [CeL]lm-3)-and [CeL2]<2m-3>-was confirmed by means of absorption spectroscopy, where Lm~denotes an unsaturated heteropolytungstate anion of P, Si, or Ge, while clear evidence for the complexation of BW11O399-was not obtained. Electrochemical behaviors of heteropolytungstocerates(III) were studied by cyclic and differential pulse voltammetry in aqueous solution. The redox potential of the cerium(IV/III) couple was considerably lowered (below +1 V vs Ag/AgCl) upon coordination of heteropolytungstate in aqueous solution at pH 4.5. The magnitude of the potential shift for [CeL]lm"3>" increased in the order PWnOgg7-, P2W1706i10-, GeWnOag8-, and SiWuOag8-. A similar trend was observed for [CeL2]12m-3>-with larger potential shift than those of [CeL]lm-3>-. The shift of the redox potential for cerium(IV/III) is caused primarily by the large negative charge of the unsaturated heteropolytungstate.