For producing synthesis gas by autothermal reformation of gaseous, liquid and/or solid fuels, the fuel is reacted with an oxidizing agent in a reaction space at a pressure of 10 to 120 bar and a reaction space temperature of 800 to 2,000° C. to obtain synthesis gas, wherein the oxidizing agent is introduced centrally in the upper region of the reaction space and wherein a flame is formed in the reaction space. The oxidizing agent is introduced into the reaction space separate from the fuel.