TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The catalyst is a slurry of (III) in (II), which is added to (I) in amounts of 0.3-6.0 wt% based on (I). A mixture of (I), (II) and (III) is subjected to temperature-graduated processing stages for thermocatalytic liquefaction, and the resulting gases and vapours are condensed in stages to obtain liquid fuel, the heat of condensation being used for drying (I) immediately after pulverization. Pulverized (I) is subjected to (a) soaking in (II) and heating with circulating heating oil, (b) further pulverization to form microfibrils, (c) mixing with catalyst (III), (d) further heating as in (a) to decompose the polymer structure etc., (e) further heating with circulating oil to polymerise any monomers, (f) further heating to evaporate the products and (g) gradual cooling of the evaporated products to form fuel. Vapour and gas from stages (a), (d), (e) and (f) are passed to a heat exchanger unit (HEU); in stage (a), residual water is evaporated and the lignin is softened, while the volatile wood components are dissolved in (II) and the resulting vapour is passed to an HEU. In stage (d), the polymer structure and lignin are decomposed primarily to simple molecules, with ring cleavage at the oxygen atoms and catalytic rearrangement of the oxygen atoms resulting in the conversion of carbon monoxide to dioxide, gaseous products which are unreactive and insoluble in (II) being passed to an HEU. Stage (e) involves the polymerisation of monomers to 6-25C alkanes, with unreactive, insoluble products being passed to an HEU. Stage (f) involves the final evaporation of products which are then passed to an HEU together with liberated gases; part of the remaining (II) is transferred to a separator to remove solids with a particle size of more than 10-20 microns and the unseparated solid (below 10-20 microns) plus the remaining (II) is used as fuel in a combustion engine (preferably a diesel engine) from which fine ash is removed on a particle filter; in this case, heating oil is used for heating and the off-gas from the engine is transferred to a heating oil-waste heat boiler for heat exchange with the circulating oil. A second part of the remaining (II) in stage (f) is recycled for heating in stage (a). A third part of (II) is passed to a solid separator together with the solid separated from the first part of (II), after which the residual liquid (II) is evaporated off from the alumina and other minerals by heating. Off-gas from the engine (above) is filtered after passing through the boiler and released to air. Heat exchange between vapour and drying air occurs in the HEU and is used for drying (I). In stage (a), the HEU has a first section through which drying air passes, operating with an outlet temperature of 160-200degreesC and fixing the cut point between gas oil/diesel and gasoline/water, from which first section the condensate and uncondensed gases including water vapour are passed to a liquid separator/after-cooler in which the gas oil/diesel fraction is separated; the still uncondensed gas and water vapour then passes to a second HEU section through which drying air passes (outlet temperature about 30degreesC) and in which the residual gas plus water vapour condenses, the condensate being taken to a water separator for separating the gasoline from water. Stages (a), (d), (e) and (f) are carried out at 120-150, 150-250, 250-300 and 300-370degreesC respectively. (II) is a high-boiling heavy oil which is produced routinely in the plant and is continuously used as fuel in the diesel engine. EXAMPLE - A batch plant was supplied with dried wood chips at 4 kg/hour plus aluminum oxide catalyst (containing montmorillonite, illite and/or smectite) at 200 g/hour, and operated by the method according to the invention for 10 hours at 350degreesC. The isolated products comprised (based on starting material): 33-43 wt% fuel, 15-20 wt% carbon, 20-25 wt% water and 15-20 wt% gas (43% carbon dioxide, 32% carbon monoxide, 7% methane, 9% nitrogen, 1% hydrogen), corresponding to an energy utilization (starting material = 100%) of 70-80% fuel, 20% carbon and 5-10% gas.