Heteropoly molybdates containing covalently bound organic moieties have been prepared and characterized by chemical analysis and spectroscopic measurements. Salts of the anions RP2Mo5O214-, where R H, CH3, C2H5, C6H5, C2H4NH3 and pCH2C6H4NH3, are stable in aqueous solution at pH 2.5 - 5. The new complexes have a structure related to that of P2Mo5O236- and are not reducible to heteropoly blue species. The amino derivatives are the first examples of zwitterionic heteropoly complexes. Applications of organic derivatives of heteropoly complexes, of which the molybdophosphonates are the first examples, are briefly considered.