NOVELTY - Energy production device (D) with one chamber (100) containing thermal means (200) of producing hydrogen, means (300) of burning the hydrogen produced and means (400) of recovering the heat produced.    USE - Producing energy by decomposition of water    ADVANTAGE - Combining the production of energy with the decomposition of water into oxygen and hydrogen allows more energy to be recovered by burning the hydrogen before it recombines with the oxygen    DETAILED DESCRIPTION - The means of producing hydrogen are formed of a block of refractory material (210) at high temperature on the surface of which water is deposited using a device (22) which ensures drop-by-drop or ribbon supply. The block of refractory material is preformed to make steps (211, 212, 213, 214, 215, 216) over which the water supplies are placed (221, 222, 223, 224, 225, 226). The number of water supply outlets increases when the steps are higher. Each step sticks out in a ledge above the next step down so the heat produced by burning the hydrogen on one step is better used heating the next step up. The chamber (100) incorporates means of displacing the different gases produced, using a ventilation sub-assembly (500). The means of recovering heat (400) is an exchanger with tubes filled with water.    An INDEPENDENT CLAIM is also included for a process for operating the above device, by heating the refractory material in a first period to a temperature allowing water to decompose into hydrogen and oxygen by contact, and using the heat released by burning hydrogen over a second period to maintain the temperature.    DESCRIPTION OF DRAWING(S) - The figure shows the device    Chamber (100)    Means of producing hydrogen (200)    Refractory material (210)    Step (211)    Step (212)    Step (213)    Step (214)    Step (215)    Step (216)    Water supply (220)    Water supply outlet (221)    Water supply outlet (222)    Water supply outlet (223)    Water supply outlet (224)    Water supply outlet (225)    Water supply outlet (226)    Means of burning hydrogen (300)    Ventilation sub-assembly (400 Means of recovering heat (500)