NOVELTY - The process of preparing fuel gas (46) having a calorific value of 1 MJ/Nm3, comprises performing a reaction between an oxidizing gas comprising water vapor (30 vol.%), oxygen or carbon dioxide with organic matter in contact with a silicate melt. The organic matter is present in sufficient quantity (10%) with molar percentages of hydrogen and carbon monoxide. The silicate melt is present at a temperature of 800-1700 degrees C. The oxidizing gas and the calorific electric supply are generated by submerged combustion. The fumes of the combustion comprise a fuel gas.    USE - The process is useful for preparing fuel gas either directly from solid or liquid such as biomass and/or wastes such as tires, plastics, automotive crushed residue, sludge and household wastes, or indirectly from the materials that are previously processed after the first operation of pyrolysis.    ADVANTAGE - The process is capable of easily, automatically and continuously preparing the fuel gas using an effective and compact device.    DETAILED DESCRIPTION - The process of preparing fuel gas (46) having a calorific value of 1 MJ/Nm3, comprises performing a reaction between an oxidizing gas comprising water vapor (30 vol.%), oxygen or carbon dioxide with organic matter in contact with a silicate melt. The organic matter is present in sufficient quantity (10%) with molar percentages of hydrogen and carbon monoxide. The silicate melt is present at a temperature of 800-1700 degrees C. The oxidizing gas and the calorific electric supply are generated by submerged combustion. The fumes of the combustion comprise a fuel gas, which is created by same process and mixed with other gases. The fuel gas is heated by passing it under a lowered arch before evacuation. The silicate is contained in a tank and regularly discharged from the tank. Glass materials are introduced regularly to supply to a silicate bath (45). An INDEPENDENT CLAIM is included for an industrial device for preparing fuel gas.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an industrial device for preparing the fuel gas.    User furnace (41)    Exhaust fumes (42)    Boiler (43)    Silicate bath (45)    Fuel gas. (46)