NOVELTY - Cell for electrochemical process, comprises a planar porous component inserted between an ion-exchange membrane and a gas diffusion electrode and fed with at least one liquid reactant percolating in its interior. The porous planar component comprises a plastic material from the group of high-density polyethylene and fluorinated plastics.    USE - The invention is used for electrochemical process, e.g. electrolysis of alkaline halides or alkaline sulfates, production of hydrogen peroxide, and the generation of electric current in the electrochemical cell. It is used in electrolyzer (claimed). It can also be used for the production of electric energy with alkaline fuel cells.    ADVANTAGE - The constitutive materials of the porous planar component have high mechanical resistance at high temperature and chemical inertia towards hot concentrated caustic soda, and in the presence of peroxide traces. Thus, it is not capable of producing harmful contamination of the membranes. The materials are highly hydrophobic and thus, their use is in strong contrast to what proposed by the prior art technique, according to which hydrophilicity is an essential feature. The ascending gas flow effectively displaces the hydrogen formed in small amounts as a side product of the oxygen consuming reaction, avoiding dangerous build-ups in stagnant zones. The planar component keeps its shape unaltered, and in particular as concerns both the void to occupied volume ratio and the porosity, without being squeezed by the elastic supports or the pressure differential employed to keep in intimate contact the membrane-planar component-oxygen cathode-current distributor assembly. It is possible to operate the cells equipped with oxygen cathode in full safety conditions, also when the quantities of generated hydrogen are relevant and capable of forming unstable mixtures even in case of optimal mixing. The operating stability of the cells is exceptionally high.    DETAILED DESCRIPTION - Cell for electrochemical process, comprises an anodic compartment (2) containing an anode (3) and a cathodic compartment (7) containing a cathode (10) separated by an ion-exchange membrane (16); a gas diffusion electrode in contact with the surface of the current distributor (11); and a planar porous component (9) inserted between the membrane and the gas diffusion electrode and fed with at least one liquid reactant percolating in its interior. At least one of the two anodic and cathodic compartments contains an assembly consisting in a current distributor connected to the wall of the relative compartment by supports (4, 12). The porous planar component comprises a plastic material from the group of high-density polyethylene and fluorinated plastics.    An INDEPENDENT CLAIM is also included for:    (1) an electrolyzer consisting in a modular arrangement of elementary cells;    (2) Production of hydrogen peroxide using the cell;    (3) An electrochemical process comprising electrolysis of alkaline halides or alkaline sulfates in the cell.    DESCRIPTION OF DRAWING(S) - The figure is a side view of the cell for electrochemical process.    Anodic compartment (2)    Anode (3)    Supports (4, 12)    Cathodic compartment (7)    Planar porous component (9)    Cathode (10)    Current distributor (11)    Ion-exchange membrane (16)