Hydrogen is a promising vector in the decarbonization of energy systems, but more efficient and scalable synthesis is required to enable its widespread deployment. Towards that aim, Serra et al. present a microwave-based approach that allows contactless water electrolysis that can be integrated with hydrocarbon production. Supplying global energy demand with CO2-free technologies is becoming feasible thanks to the rising affordability of renewable resources. Hydrogen is a promising vector in the decarbonization of energy systems, but more efficient and scalable synthesis is required to enable its widespread deployment. Here we report contactless H-2 production via water electrolysis mediated by the microwave-triggered redox activation of solid-state ionic materials at low temperatures (<250 degrees C). Water was reduced via reaction with non-equilibrium gadolinium-doped CeO2 that was previously in situ electrochemically deoxygenated by the sole application of microwaves. The microwave-driven reduction was identified by an instantaneous electrical conductivity rise and O-2 release. This process was cyclable, whereas H-2 yield and energy efficiency were material- and power-dependent. Deoxygenation of low-energy molecules (H2O or CO2) led to the formation of energy carriers and enabled CH4 production when integrated with a Sabatier reactor. This method could be extended to other reactions such as intensified hydrocarbons synthesis or oxidation.