CH4 and air or O2 are caused to react together to give steam and CO2; the mixture of gases then combine in the presence of a catalyst to give CO and H2. Unheated CH4 (1,000 m.3 per hr.) and 520 m.3 O2 are passed into the conical bottom of a reactive vessel of 2-in. diameter containing porcelain pieces surmounted by a layer of a heated oxidation catalyst, such as Pt gauze, on the top of which lies 1 m.3 of a Ni catalyst. The mixture of CO and H2, 3,000 m.3 per hr., contains 0.5% CH4.