To prevent the liquid electrolyte from penetrating into the porous support while at the same time preserving or increasing the power density of the fuel cell, before the liquid electrolyte is deposited, at least a part of the walls delineating the pores of said support is covered by a film formed by a material presenting a contact angle of more than 90° with a drop of said liquid electrolyte. Said film further presents a thickness enabling passage of the reactive fluid in the pores of the support.