NOVELTY - A carbonaceous material is pyrolyzed to produce volatiles and char, char and volatiles are separated. The char is gasified and the volatiles are reformed to produce a product gas, and the partially reformed volatiles and/or product gas are passed through a product-gas cleaning zone.    USE - Gasification of carbonaceous material e.g. biomass, into gaseous fuel.    ADVANTAGE - The method passes partially reformed volatiles and/or product gas through a catalyst bed, which results in several effects including the removal of tar residues and other impurities, such as inorganic contaminants, and increasing the hydrogen content of product gas by performing the water-gas-shift reaction, thus producing a clean product gas. The spent or partially spent char or char-supported catalysts may be returned to the field as a soil conditioner, a source of nutrients, and/or for carbon biosequestration. The method enables gasification of low-rank carbonaceous materials in a single gasification vessel integrating gasification with hot gas cleaning. The interactions between volatiles and char during char gasification, leading to an increased rate of char gasification. Direct oxygen consumption by volatiles and their reforming products is minimized. The direct reaction of char with oxygen in the char gasification zone is promoted to generate the heat required for various reactions within the gasification vessel, thus recuperating the thermal energy of the char gasification products in the form of chemical energy as the product gas. The overall consumption of oxygen is minimized for maximized gasification efficiency. The volatilization of inorganic species, in particular alkali and alkaline-earth metallic species, is minimized. The catalyst is used to promote the water-gas-shift reaction thus increasing the hydrogen content of the final product gas without the problems associated with catalyst deactivation, regeneration and disposal.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) treatment of raw product gas produced from gasification of low-rank carbonaceous materials;    (2) gasification system (20); and    (3) apparatus (30) for pyrolyzing and partially gasifying carbonaceous materials.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the gasification method of carbonaceous material.    Gasification system (20)    Char gasification zone (23)    Reforming zone (25)    Catalyst bed (26)    Apparatus for pyrolyzing and partially gasifying carbonaceous materials (30)