A device having a water vapor microelectrolyzer cell including microstructured parallel electrodes where the water splitting reactions can take place, the microstructured electrodes being covered by a thin layer of solid-state ion conducting material to allow for the conduction of protons during the device operation, while permitting the diffusion of water from the vapor phase into the electrodes, as well as the diffusion of evolved oxygen and hydrogen gases from the electrodes into the vapor phase environment above the ion-conductor film.