Abstract: The present invention provides a process for the production of carbon monoxide and hydrogen by partial oxidation of a methane-containing feedstock in the presence of a molecular oxygen-containing gas, wherein said process comprises (a) providing a pre-heated, mixed feedstream comprising said methane-containing feedstock and said molecular oxygen-containing gas, (b) subsequently mixing said pre-heated, mixed feedstream with a diluent, said diluent being pre-heated to a temperature of at least 400° C., to produce a diluent mixed feedstream comprising at least 10% by volume of diluent, and (c) contacting said diluent mixed feedstream with a catalyst suitable for the partial oxidation of the methane, to provide a product stream comprising carbon monoxide and hydrogen.