Abstract: A method for producing a fuel cell core including: providing two identical subassemblies each including a substrate and a current collector removably arranged thereon, depositing an ionic liquid or pasty polymerizable membrane on at least one of the subassemblies in such a way that the collector thereof is completely covered, applying the subassemblies one against the other so as to obtain an assembly having a solidified membrane with the two collectors incorporated, face to face, in this membrane, and detaching the two substrates from the collectors.