Abstract: A method of, and apparatus for, coking or carbonizing fluent or flowable carbon-containing material, such as wood, peat, residues, wastes or the like, by means of gases in an inclined treatment chamber through which the material moves from the top towards the bottom under the influence of gravity while utilizing the flow action of the material while exceeding the natural angle of repose of the material. Gas is conducted from the bottom towards the top in countercurrent flow to the material through the treatment chamber. The gases, constituting a mixture of an infed dosed supply of air and distillation gas escaping out of the material in gaseous state into the hot gas mixture, are exclusively conducted upwardly in the treatment chamber over the material in direct contact therewith owing to the natural rise or lift and the heat needed for coking or carbonizing the material is exclusively produced in the treatment chamber by combustion of the distillation gas with the infed air.