The invention concerns a method for producing a gas mixture containing hydrogen and carbon monoxide, and optionally nitrogen, from at least a hydrocarbon such as methane, propane, butane or LPG or natural gas, which comprises performing a partial catalytic oxidation of one or several hydrocarbons, at a temperature of 500 C., at a pressure of 3 to 20 bars, in the presence of oxygen or a gas containing oxygen, such as air, to produce hydrogen and carbon monoxide. Recuperating the gas mixture, which can subsequently be purified or separated, by pressure swing adsorption, temperature swing adsorption or by permeation, to produce hydrogen having a purity of at least 80% and a residue gas capable of supplying a cogeneration unit. In another embodiment, the gas mixture can subsequently be purified of its water vapor impurities and carbon dioxide to obtain a thermal treatment atmosphere containing hydrogen, carbon monoxide and nitrogen.