Abstract: In the method for thermal biomass processing, comprising charging the material in a converter, pyrolyzing said material at a temperature ranging between 650 and 950° C. in the medium of a reducing gas, feeding of steam after the pyrolysis reaction has been completed, and isolating the resultant solid residue, reducing gas is prepared by combusting a hydrocarbon fuel at an air consumption factor &agr; ranging from 0.85 to 1.1, and by mixing the resultant combustion products together with the biomass pyrolysis gases, the ratio between said gases and said combustion products being (1-3):1.