The talk will report on recent developments in our laboratory in electrochemical reactions catalyzed by polyoxometalates. First, combining a specifically designed di-Re(I) catalyst with H3PW12O40 in a hybrid compound, we show that upon electrochemical reduction of the polyoxometalate at a relatively low negative potential of 1.3 V versus Ag/AgNO3, photoexcitation of the polyoxometalate with visible light is enabled through excitation of the intravalence charge transfer band. This leads to electron transfer to the Re(I) catalyst for the overall photoelectrochemical reduction of CO2 to CO. Conceptually this means that such a polyoxometalate can be an electron “shuttle” between a water oxidation reaction on the one hand that produces electrons/protons and O2 and a CO2 photoreduction catalyst. Second, tri-transition metal substituted polyoxometalates such as b-[SiW9O37(CuIIH2O)3]10– are shown to be outstanding electrocatalysts for the selective reduction of CO2 to CO with a turnover frequency by foot-of the wave analysis of nearly 3000 sec–1 without addition of an acid. Very high stability in electrolytic reactions was observed with stable currents for a period of 24h. at a potential of 2.5 V versus Fc/Fc+ and a Faradaic efficiency of >90%. Step-wise reduction of the catalyst followed by UV-vis and EPR spectroscopy indicates that the active species is a likely a four-electron reduced polyoxometalate. Additionally, similar compounds such as b-[SiW9O37(FeIII 2NiIIH2O)3]10– are shown to be functional models of CO hydrogenase/CO2 dehydrogenase enzymes that also have Fe-Ni active sites. As in the enzyme, the CO oxidation is one order of magnitude faster than the CO2 reduction. An iron-tungsten oxide inorganic molecular catalyst, a Keplerate polyoxometalate with a capsular structure, with a short-hand notation, {Fe30W72}, was used for the cathodic oxidation of simple hydrocarbons such as ethane to acetic acid, ethylene to formaldehyde and benzene to phenol in water. The {Fe30W72} capsule is stabilized in the core by sulfate/bisulfate anions providing a protic environment where three iron atoms are located at each of the twenty pores of the capsule leading to a unique and potent active site for the aerobic hydrocarbon oxidation. This is the first example of the reductive electrochemical activation of O2 that functionally mimics the reactivity of iron-based monooxygenase enzymes. Turnover frequencies based of 300-600 min1– were obtained based on the surface area of the cathode. With a graphitic carbon fiber cathode and Pt anode Faradaic efficiencies of ~60% at a cell potential of 1.8 V were typically obtained where the uncoupled reduction of O2 to water was minimized. Extensive mechanistic research using EPR spectroscopy, kinetic isotope effect measurements as well as reactions of model compounds such a 1,4-difluorbenzene, indicate the intermediacy of a highly active high spin iron-oxo species as the oxygenating species.