The invention is directed to a process to prepare a mixture of hydrogen and carbon monoxide by performing a partial oxidation on a hydrocarbon feed using a multi-orifice burner provided with an arrangement of separate passages, wherein the hydrocarbon flows through a passage of the burner, an oxidiser gas flows through a separate passage of the burner and wherein the passage for hydrocarbon feed and the passage for oxidiser gas are separated by a passage through which a moderator gas flows and wherein the exit velocity of the moderator gas is greater than the exit velocity of the oxidiser gas.