The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are key catalytic processes for sustainable energy technologies, such as water electrolysis or fuel cells. Here, a novel metal oxide-nanostructured carbon composite is reported, which acts as OER and ORR electrocatalyst under technologically relevant conditions. A facile synthetic process allows the deposition of a molecular manganese vanadium oxide precursor, [Mn4V4O17(OAc)3]3-, on reduced graphene oxide. Simultaneously, the precursor is converted into insoluble nanostructured solid-state Mn-V-oxide catalysts. Control of the synthetic conditions allows tuning of the electrocatalytic properties of the composites, leading to excellent and stable electrochemical reactivity. The electrocatalytic ORR and OER activity was evaluated in alkaline aqueous electrolyte and showed performance comparable with commercial Pt/C electrocatalysts. The study thus demonstrates how polyoxometalate precursors based on earth-abundant elements can be deposited on nanostructured carbon to give high-performance OER/ORR catalysts for alkaline water electrolysis. A new class of composite catalysts can in future be accessed by a facile fabrication route.