This invention is directed to a method of oxygenating hydrocarbons with molecular oxygen, O2, as oxidant under electrochemical reducing conditions, using polyoxometalate compounds based on the so-called Keplerate capsules, such as [{(WVI)WVI5O21(SO4)}12{(Fe(H2O))30}(SO4)13(H2O)34]32− or [{(MoVI)MoVI5O21)(X′1)6}12{FeIII(H2O)(X1)}30] or solvates thereof as catalysts, wherein X′1 and X1 are each independently selected from H2O, Mo2O82−, Mo2O92−, CH3COO− (acetate), or any combination thereof.