Abstract: The present invention relates to a method of processing residual gases containing sulfur, hydrogen sulfide, and sulfur oxides and supplied from Claus plants or other surfur-producing installations, wherein the Claus plant is operated along or in connection with an ammonia decomposition plant in which ammonia-containing heated gases are directed through a decomposition zone which is free or filled with heat-resistant filler bodies or with a catalyst material, and the ammonia is decomposed into nitrogen and hydrogen and, thereupon, the gases are cooled and washed. The residual gases containing sulfur, hydrogen sulfide, sulfur oxides and ammonia-containing heated gases are fed to an ammonia decomposition chamber where the ammonia is decomposed into nitrogen and hydrogen and the residual gases react to produce a product gas enriched in hydrogen sulfide, the hydrogen for the reaction being supplied by the decomposition of ammonia.