The technical problem of the invention is to create a process where the second layer is of higher sintering quality and improved waste gas values are achieved. The process according to the invention for the thermal transformation of materials containing organic substances in a two-layer sintering process, charges the second layer (8) containing the organic substances at a maximum layer thickness of 20% of the first layer after ignition of the first layer (1) and thermally treats the second layer when the combustion zone of the first layer ensures the combustion of the organic substances coming from the second layer and entering the combustion zone of the first layer, following the pressure difference, is least 70%. The area above the combustion zone of the first layer still must have a temperature preventing the organic substances coming from the second layer and entering the first layer from condensing.