Three new organotin derivatives of polyoxometalates have been obtained by reaction between the trilacunary precursors [PW9O34]9− and [AsW9O34]9− and organotin trichlorides RSnCl3 (R=Me, Bu) in aqueous solution. The compounds were characterized using elemental and thermogravimetrical analysis, UV, IR, Raman and multinuclear (1H, 13C, 31P) NMR spectroscopy, ESI‐MS and cyclic voltammetry. Ion‐exchange, and ESI‐MS experiments provided evidence for covalent, inner‐sphere bonding of organotin groups to the trilacunary [XW9O34]9− heteropolyanions. Cyclic voltammograms of all three organotin complexes exhibited two pairs of reduction/oxidation waves with negative half‐wave potential (E1/2) values. These waves were attributed to redox processes corresponding to the polyoxotungstate framework.