Abstract: A high pressure thermal hydrolysis process is described which comprises heating acid waste streams resulting from the manufacture of cyanuric acid and chlorinated derivatives of cyanuric acid, containing cyanuric acid and amino-substituted cyanurates, in a pressure vessel, at a temperature of from about 225.degree. to about 275.degree. C, to effect decomposition of these materials into ammonia and carbon dioxide. This process provides an effective pollution control means, compatible with existing commercial facilities.