Abstract: Waste gas, in particular from plants for the chemical vapor-phase deposition and for the separation and etching by plasma processes, is purified from toxic agents by a method in which partial processes of the purification, such as thermal decomposition and oxidation, sorption of solid and gaseous reaction products, hydrolysis and cooling, are combined to act in a single reaction chamber. The reaction products of the waste gas burnt in a flame are led, directly in the combustion chamber, through a space filled with a finely dispersed liquid. This liquid forms a liquid film on all parts and inside walls of the reaction chamber. In a combustion chamber with a burner, the mentioned liquid distribution is obtained by a spraying device.Effective purification from toxic agents, and little corrosion of the components of the reaction chamber are achieved, any growth of solid reaction products in the combustion chamber being avoided.