Abstract: A process for effecting thermal decomposition of explosive nitric acid esters in wastewater effluents of the explosives industry wherein no additional by-products are produced and wherein the danger of explosions is avoided. In this process, the dissolved esters are exposed to a temperature of between 150.degree. and 300.degree. C. under pressure lying above the boiling pressure of the wastewater. During this step, the nitric acid esters are completely decomposed, and the wastewater treated in this way can then be passed on to further processing and purification. In a preferred embodiment, the hot wastewater exiting from a decomposer unit is exploited for preheating the effluent before it enters the decomposer unit.