NOVELTY - The device for production of hydrogen from a dehydrogenation chemical reaction of hydrogenated compounds, comprises a catalytic reactor, an unit for heating the reactor to maintain the catalytic dehydrogenation reaction, an unit for cooling and condensing the dehydrogenation reaction products at an outlet of the reactor, and an unit for vaporizing and overheating the hydrogenated compounds in an upstream of the reactor. An endothermic dehydrogenation reaction is carried out in the reactor.    USE - Useful for the production of hydrogen from dehydrogenation chemical reaction of hydrogenated compounds.    ADVANTAGE - The device increases effectiveness of the heat exchanger without increasing the size of the exchanger.    DETAILED DESCRIPTION - The device for production of hydrogen from a dehydrogenation chemical reaction of hydrogenated compounds, comprises a catalytic reactor, an unit for heating the reactor to maintain the catalytic dehydrogenation reaction, an unit for cooling and condensing the dehydrogenation reaction products at an outlet of the reactor, and an unit for vaporizing and overheating the hydrogenated compounds in an upstream of the reactor. An endothermic dehydrogenation reaction is carried out in the reactor. The vaporizing and overheating unit comprises a catalytic product to partially initiate the dehydrogenation reaction for reducing parasitic reactions, and an evaporation circuit. The parasitic reactions inhibit the dehydrogenation reaction in the reactor. The evaporation circuit comprises an inlet duct to introduce the hydrogenated compound into the reactor under pressure, a piezoelectric type injector (24) diffusing the hydrogenated compound under pressure in the form of liquid, an evaporator (6) to evaporate the hydrogenated compound, and a superheater (8) arranged in a downstream of the evaporator to transfer the vapor of the hydrogenated compound up to a temperature allowing its decomposition. A lower temperature zone contains the catalytic product to partially initiate the dehydrogenation reaction and to inhibit the parasitic reactions. The injector is useful to form a spray of hydrogenated compound in the evaporator to support the evaporation. The cooling and the condensing unit comprises a condensation circuit having an air cooler thermally coupled with superheater in a heat exchanger, a condenser (14) thermally coupled with the evaporator in the heat exchanger, and an evacuation unit separately collecting the dehydrogenation reaction products in the form of liquid and/or gas. The superheater communicates dehydrogenated reaction products to the overheated hydrogenated compound. The heat exchangers, air cooler/superheater and evaporator/condenser are in the shape of inverted rafter plates to increase the heat exchange surface. The catalytic reactor comprises another reactor in which an exothermic reaction of combustion mixture of fuel and comburant takes place. The two reactors are arranged to have a common heat exchange face for transferring heat, which maintains the endothermic and exothermic reactions. The two reactors are thermally coupled with heat exchanger in the shape of inverted rafter plates or coupled with microchannels to increase the heat exchange surface. The catalytic product contained in the superheater has a same nature as the product contained in the reactor to initiate the dehydrogenation reaction. The catalytic products comprise platinum and/or palladium deposited directly on the walls of the catalytic reactor and in the superheater zone. The partial dehydrogenation reaction takes place in the superheater is initiated with height of a fraction not exceeding 30% of total quantity of evaporated hydrogenated compound present in the superheater.    DESCRIPTION OF DRAWING(S) - The diagram shows the device for the production of hydrogen (Drawing includes non-English language text):    Evaporator; (6)    Superheater; (8)    Condenser; (14)    Air inlet duct; (17)    Injector. (24)