During the production of a lithium microbattery, the electrolyte containing a lithiated compound is formed by successively depositing an electrolytic thin film, a first protective thin film that is chemically inert in relation to the lithium, and a first masking thin film on a substrate provided with current collectors and a cathode. A photolithography step is carried out on the first masking thin film in order to create a mask for selectively etching the first masking thin layer, and the first protective thin layer and the electrolytic thin film are then selectively etched in such a way as to form the electrolyte in the electrolytic thin film. This technique enables the electrolyte to be formed by photolithography and etching without causing any damage thereto.