Abstract: Lump wood is carbonized in a shaft retort, which is flown through by hot rinse gas. The wood is charged to the retort at its top. Wood charcoal is withdrawn from the lower portion of the retort. An exhaust gas which contains gases and vapors produced by carbonization is withdrawn from the top end of the shaft retort and is directly fed to a combustion chamber. In a first section of the combustion chamber, the exhaust gas is combusted with air at an understoichiometric to stoichiometric rate at temperatures from 800.degree. to 1250.degree. C. Part of the combustion gas is withdrawn from that first section of the combustion chamber and is cooled to temperatures from about 450.degree. to 900.degree. C. and is fed as a rinse gas to the shaft retort. In a second section of the combustion chamber, the exhaust gas is completely combusted with air supplied at an overstoichiometric rate.