TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The temperature in (III) is 800-1100degreesC and (IV) is 350-600degreesC. The pressure in (III) and (IV) is 1-100 bar absolute. The ratio of oxygen molecules supplied to (III) to carbon atoms in (I) supplied to (III) and (IV) is 0.1-0.7. The ratio of steam supplied to (III) and (IV) and carbon atoms in (I) supplied to (III) and (IV) is 1-5. The ratio of (I) supplied to (III) and (I) supplied to (III) and (IV) is 0.4-0.8.The first and the second gaseous stream of (I) comprise natural gas, methane, ethane, propane and/or liquid petroleum gas (LPG). The molecular-oxygen containing gas is substantially pure oxygen, which is supplied to (III) through a nonporous, dense layer of mixed electronic ionic conductor, which is located in (III), the dense layer forming a tube having a retentate side at the inside of the tube and a permeate side facing the catalyst bed, where the air is fed to the inside of the tube and oxygen-depleted air is discharged from the inside of the tube. The air is fed to the inside of the tube via an air supply conduit that extends through (IV). The oxygen-depleted air is discharged from the inside of the tube via a discharge conduit that extends through (IV).The hydrogen-permeable selective membrane comprises palladium, platinum or their alloys. The inlet for molecular- oxygen containing gas is in the form of a nonporous, dense layer of mixed ionic electronic conductor that is located in (III), the dense layer forming a tube having a retentate side at the inside of the tube and a permeate side facing the catalyst bed, where the air inlet conduit is connected to one end of the tube and an oxygen depleted air discharge conduit is connected to the other end of the tube.Preferred Components: The mixed electronic ionic conductor is a metallic oxide of the formula ABO3-delta.A = calcium, strontium, barium, yttrium or lanthanum;B = chromium, manganese, iron, cobalt, nickel or copper; anddelta = 0-0.5.The fuel cell is a proton exchange membrane fuel cell.