Abstract: A method of manufacturing gas diffusion layers (GDL) with a defined pattern of hydrophobic and hydrophilic regions is used to produce electrically conductive porous materials with distributed wettability. The method includes a) Coating the external and internal surfaces of a porous base material made of carbon fiber or Titanium with Fluoroethylene-Propylene (FEP) and/or perfluoroalkoxy (PFA) and/or Ethylene-Tetrafluoroethylene (ETFE) or any other hydrophobic polymer; b) Exposing the coated material to irradiation through a blocking mask such that only parts of the coated porous material are exposed; and c) Immersing the previously exposed material in a monomer solution and heating to a temperature higher than 45° C., resulting in the graft co-polymerization of monomers on the FEP layer.