NOVELTY - The perfluorinated sulfonic acid polymer membrane comprises: a porous surface layer (20); a non-porous dense bottom layer (10) formed at a bottom of the surface layer; a catalyst layer formed on the porous surface layer or on the bottom layer; and an ion conductive polymeric membrane formed on the surface layer. The ion conductive polymeric membrane is a second perfluorinated sulfonic acid polymer membrane having an ion exchange capacity different from the ion exchange capacity of perfluorinated sulfonic acid polymer of the perfluorinated sulfonic acid polymer membrane.    USE - The perfluorinated sulfonic acid polymer membrane is useful in a fuel cell, a sensor, an electrolytic cell, a gas separator, and an humidifier (claimed), where the fuel cell comprises a polymer electrolyte membrane fuel cell and a direct methanol fuel cell.    ADVANTAGE - The perfluorinated sulfonic acid polymer membrane reduces possibility of delamination occurring between the electrolyte membrane and the catalyst layer during humidification cycle of the fuel cell, enhances water transport at the interface between gas and the electrolyte membrane, increases reverse diffusion of water as a reaction product to help humidification, and provides an increased interfacial area.    DETAILED DESCRIPTION - The perfluorinated sulfonic acid polymer membrane comprises: a porous surface layer (20); a non-porous dense bottom layer (10) formed at a bottom of the surface layer; a catalyst layer formed on the porous surface layer or on the bottom layer; and an ion conductive polymeric membrane formed on the surface layer. The ion conductive polymeric membrane is a second perfluorinated sulfonic acid polymer membrane having an ion exchange capacity different from the ion exchange capacity of perfluorinated sulfonic acid polymer of the perfluorinated sulfonic acid polymer membrane. The polymer membrane further comprises a sulfonated hydrocarbon-based polymeric membrane, and an anion conductive polymeric membrane. The two perfluorinated sulfonic acid polymer membranes are laminated such that the dense bottom layers of the membranes face each other. An INDEPENDENT CLAIM is included for a method for manufacturing a perfluorinated sulfonic acid polymer membrane.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic sectional view of a perfluorinated sulfonic acid polymer membrane.    Non-porous dense bottom layer (10)    Porous surface layer. (20)