NOVELTY - A gas and oxygen reactor (1) comprises feeding ducts (10, 11) to convey a flow of fuel gas (G2) and a flow of oxidizing gas (S). The second feeding ducts are separate from a pre-combustion chamber (4), and their respective downstream outlets lead directly into a main combustion chamber (5) where mixing and combustion of a combusted first flow within the second flow of fuel gas and flow of oxidizing gas takes place.    USE - Reactor for the production of a reducing gas, particularly for the direct reduction of iron ores (claimed), or for the production of molecular H2 which is recovered deriving from the reducing operation.    ADVANTAGE - Reducing gas is produced with higher efficiency. The reactor allows the reliable transport of all the combustion gas mixture components. Undesired combustion products are reduced, avoiding the need for expensive filtering operations. The need for increasing the energetic potential of the reactor through pressure is eliminated, allowing working at a lower pressure.    DETAILED DESCRIPTION - A gas and oxygen reactor (1) comprises a pre-combustion chamber (4) and a main combustion chamber (5) communicating with and placed downstream of the pre-combustion chamber, both having ignition devices, first feeding ducts (2, 6) for conveying a first flow of fuel gas (G1) and oxygen (O) into the pre-combustion chamber, second feeding ducts (10, 11) for respectively conveying a second flow of fuel gas (G2) and a flow of oxidizing gas (S). The second feeding ducts are separate from the pre-combustion chamber along their extension and their respective downstream outlets lead directly into the main combustion chamber where mixing and combustion of combusted first flow within the second flow of fuel gas and flow of oxidizing gas takes place.    An INDEPENDENT CLAIM is also included for the production of reducing compounds by the above reactor, comprising:    (a) feeding to the reactor a first portion of a hydrocarbon fuel gas with oxygen;    (b) the formation of a first mixture in the pre-combustion chamber;    (c) combustion of the first mixture to produce a combusted gas mixture;    (d) feeding to the reactor a second portion of fuel gas and a flow of oxidizing gas containing water (H2O) and/or carbon dioxide (CO2);    (e) introducing the combusted gas mixture into a main combustion chamber;    (f) introducing the second portion of fuel gas and flow of oxidizing gas in the main combustion chamber;    (g) mixing the combusted gas mixture with the second portion of the fuel gas and flow of oxidizing gas to form a second gas mixture; and    (h) combustion of the second gas mixture to form a reducing gas.    An INDEPENDENT CLAIM is also included for a reducing composition produced as above, comprising (vol.%): 55-70 H2; 25-35 CO; 1-8 H2O; 1-3.5 CO2; and 0.2-1 CH4.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional view on a plane passing through the longitudinal axis of the reactor.    Gas and oxygen reactor (1)    First feeding ducts (2, 6)    Mixing chamber (3)    Pre-combustion chamber (4)    Main combustion chamber (6)    Second feeding ducts (10, 11)    First flow of fuel gas (G1)    Second flow of fuel gas (G2)    Oxygen (O)    Oxidizing gas (S)