V(IV) and V(V) containing mixed-valence heteropolytungstogermanates have been prepared by controlled potential reduction of corresponding GeW9V3O40^7^-, their electronic spectra have been recorded. The ESR spectra of one-electron-reduced anions in solution at 340K consist of more than 40 equally spaced lines, showing that the three VO6 octahedra in both α- and β- forms are corner-shared and one of the bridging oxygen atoms is protonated at pH4.7.

Key words: HETEROPOLYACID, TUNGSTIC ACID, ELECTRON SPIN RESONANCE, STRUCTURE CHARACTERISTICS, VANADIC ACID