A method serves for the pyrolysis and gasification of substance mixtures containing organic constituents. The organic substances (4) or the substance mixture containing the organic constituents are brought into contact with a heat transfer medium, for preference the ash (5) from a combustion reactor (2) in a pyrolysis reactor (1), for preference a shaft reactor and pyrolysed. The pyrolysis coke (10) derived from the pyrolysis is combusted in a combustion reactor (2), for preference a fluidised bed reactor, under the admission of air (11). In order to improve such a method, the raw gas (6) generated by the pyrolysis is purified in a crack reactor (3), for preference by a catalyst.