NOVELTY - A thermolysis method for industrial and/or domestic waste, involving at least one drying stage followed by a thermolysis stage and a stage for combustion of the gas formed in the thermolysis to produce flue gas which is partially used in the thermolysis, additionally includes a stage for reducing the temperature of the hot flue gas.    USE - For converting a mixed charge containing organic, metallic and inert components (e.g. domestic garbage, car crushing residues, used tires, noxious industrial waste or biomass) into combustible and recyclable materials. In particular a combustible gas and a combustible solid (both useful as energy source) are obtained.    ADVANTAGE - The temperature of the hot flue gas is reduced below the dust fusion threshold, so that dust does not adhere to the metal walls of the thermolysis furnace. Reduction of heat transfer and the furnace (and consequent reduction in fuel gas production) due to deposits on the furnace walls is thus prevented, without the need for regular shut-down of the system to remove deposits or for special dust removal or scraping systems.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a corresponding plant for thermolyzing industrial and/or domestic waste by the above process, having at least one dryer (1), a waste thermolysis furnace (2), a generator (3) for flue gases (to be at least partially used in the dryer) and a heat exchanger (4), the novel feature being that the plant additionally includes a hot flue gas temperature regulation system, e.g. a system (91) for injection of sprayed or nebulized water into the flue gas.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of one form of waste thermolysis plant.    Rotary dryer (1)    Rotating tube, as thermolysis system (2)    Combustion chamber, as combustion gas generator (3)    Heat exchanger (4)    Second thermolysis tube (5)    Boiler (7)    Flue gas treatment system (8, 9)    Ground waste material (10)    Outlet cell (11)    Transporter (12)    Cyclone (13)    Ventilator (14)    Gas-solid separator (21)    Heat exchanger supply line (31)    Combustion gas circulation lines (32', 33, 52, 71, 72)    Reheated air recycling line (42)    Air circulation line (43)    Water injector (91)    Dry waste outlet line (111)    Moist air outlet line (112)    Ventilator inlet line (131)    Ventilator outlet line (141)    Separator outlet line (211)    Thermolysis gas outlet line (212)