Abstract: Ammonia is synthesized from a hydrogen and nitrogen mixture containing small concentrations of inert contaminants such as argon, methane, etc. Gases dissolved in the ammonia product normally vented and discharged from the synthesis system are returned to the synthesis loop without removal of the inert contaminants. By so doing, despite the fact that the concentration of inert gases in the synthesis loop is increased, and the concentration of ammonia in the gas mixture leaving the synthesis converter is decreased, nevertheless the total amount of ammonia produced from a given quantity of hydrogen and nitrogen is increased.