It is supposed to be possible to achieve an essentially uniform water film protecting the corresponding metal panels, in a gasification reactor for producing crude gas containing CO or H2, by gasification of ash-containing fuel with oxygen-containing gas, at temperatures above the melting temperature of the ash, wherein a reaction chamber formed by a membrane wall through which cooling medium flows, a transition area as well as a quench chamber with a slag collection container that follows in the direction of gravity are provided within a pressure container. This is achieved in that, in addition to a device (14, 15) forming a water film (16) in the quench chamber (11), at least a part of the cylinder forming the quench chamber wall (17) is designed with a double wall and with a coolant overflow (21) for additionally wetting (18) the inner surface of the quench chamber wall (17), and a tangential coolant supply (20) in the bottom area of the double walled cylinder (19) which is closed at the bottom.