A three-stage quenching and scrubbing system for treatment of hot crude gases and liquid slag after an entrained flow gasification. In the first primary stage, cooling and scrubbing water is injected such that slag can no longer adhere to the wall of the central tube and the conversion reaction of the carbon monoxide with water vapor to give hydrogen can proceed to close to the equilibrium. A secondary quenching and scrubbing stage takes the form of a bubble column, and further cooling and the deposition of coarse dust and slag are effected in a water bath. The rest of the treatment is through intensive spraying in a tertiary quenching and scrubbing the gas stage, nozzle rings for deposition of fine slag and partly of fine dust. All three quenching and scrubbing stages enable cooling of the crude gas down to the water vapor dew point determined by the plant pressure.