A burner for producing synthesis gas by partial oxidation of liquid or gaseous, carbon-containing fuels in the presence of an oxygen-containing oxidant and a moderator, which burner can be operated uncooled, i.e. without a fluid coolant being passed through the burner, is proposed. Steam or carbon dioxide or else mixtures of these materials are used as moderator. This is achieved by the feed channels being configured so that mixing of the fuel, the moderator and the oxidant occurs only outside the burner.