Abstract: The gasification process according to the invention involves an installation comprising a treatment chamber in which the materials to be treated pass successively through a drying/pyrolysis zone of variable dimensions in which a pyrolysis gas extraction takes place, then through a gasification zone of variable dimensions in which a syngas extraction takes place. The pyrolysis gas is injected into the roof of the treatment chamber (8) with an oxidizing gas, so as to generate an exothermic oxidation reaction provides the energy necessary for the pyrolysis and gasification reactions. The dimensions and/or the position of the drying/pyrolysis and gasification zones are controlled as a function of the amounts of material to be treated introduced into the treatment chamber (8), their nature and/or energy requirements.