NOVELTY - The device (1) for producing hydrogen using a plasma by electron cyclotron resonance, comprises a sealed vacuum chamber (2) to contain the plasma, a unit for injecting a high-frequency wave inside the chamber, a magnetic structure (3, 4, 5, 6) for generating a magnetic field in the chamber and generating a plasma layer according to the magnetic field lines, and a unit (11) for injecting steam in the chamber. The module of the magnetic field has a magnetic mirror configuration with an electron cyclotron resonance area. The plasma electrons partially dissociate the water molecules.    USE - The device is useful for producing hydrogen by electron cyclotron resonance, where the hydrogen is useful as energy carrier for producing petrol and other fossil fuels.    ADVANTAGE - The device is capable of efficiently, stably and continuously producing hydrogen by electron cyclotron resonance in an economical manner without producing greenhouse gas emissions and the use of carbon-carbon compounds or other chemical complexes.    DETAILED DESCRIPTION - The device (1) for producing hydrogen using a plasma by electron cyclotron resonance, comprises a sealed vacuum chamber (2) to contain the plasma, a unit for injecting a high-frequency wave inside the chamber, a magnetic structure (3, 4, 5, 6) for generating a magnetic field in the chamber and generating a plasma layer according to the magnetic field lines, and a unit (11) for injecting steam in the chamber. The module of the magnetic field has a magnetic mirror configuration with an electron cyclotron resonance area. The plasma electrons partially dissociate the water molecules introduced in the vapor phase and ionize the dissociation products. The sealed vacuum chamber comprises a first chamber comprising a selective first cryogenic condenser for freezing oxygen and a first cryogenic condenser for freezing hydrogen, and a second chamber comprising a second cryogenic condenser (8) for freezing oxygen and a second cryogenic condenser for freezing hydrogen. A unit (7) is arranged for recovering hydrogen obtained from the dissociation. A unit is arranged along an axis (AA') of steam injection for collecting non-dissociated water. The field lines generated by the magnetic structure is curved along the axis (AA') of steam injection. The non-dissociated water collection unit comprises a second chamber connected to a plasma chamber, and is present in the form of a condenser. The second chamber is separated from the plasma chamber using a diaphragm device. A system is arranged for reinjecting non dissociated water in vapor phase. A polarized grid having a mesh is arranged between the plasma of the chamber and the cryogenic condenser to control the propagation of high frequency waves. The condenser has a temperature of 6-41 K for an average pressure of 10-3 mbar to 5x 10-3 mbar in the chamber, and is a plane or finished cryogenic panel that surrounds the magnetic field lines. Each of the first and second chambers is capable of recovering oxygen and hydrogen independently from one another by regeneration or by progressive elevation of temperature so that the hydrogen passes primarily along the gas phase and recovered and then oxygen passes into the gas phase and recovered. The unit for collecting hydrogen comprises a unit for pumping hydrogen in the gas phase. The cryogenic condensers for freezing oxygen and/or hydrogen are negatively polarized to repel the electrons towards the plasma. A catalyst surface is placed between resonance zones for fixing the water molecules and increases the dissociation of water by electronic impact of plasma on the surface. The magnetic structure comprises permanent magnets having same or different magnetization direction and size, and coils at ambient temperature and/or superconducting coils having low or high critical temperature (Tc). The permanent magnet situated in the steam injection zone has same polarity of the magnet that is present in the recovery zone. The unit for injecting high frequency wave inside the chamber comprises an entrance window placed in a high magnetic field for the plasma diffusion towards the chamber thus avoiding plasma impact on the window. The mirror ratio between the maximum magnetic field and the minimum magnetic field is greater than 3.    DESCRIPTION OF DRAWING(S) - The figure shows a top view of a device for producing hydrogen.    Hydrogen production device (1)    Sealed chamber (2)    Magnetic structure (3, 4, 5, 6)    Unit for recovering hydrogen (7)    Cryogenic condenser for freezing oxygen (8)    Steam injecting unit. (11)