Abstract: A process for the complete recovery of NO from the waste gas of ammonium nitrite production, in which gases containing nitrogen oxides are absorbed in a first stage in a solution of ammonium carbonate and/or ammonium bicarbonate to form ammonium nitrite solutions and the resulting waste gas containing carbon dioxide is absorbed in a second stage in an ammoniacal, aqueous solution to form ammonium carbonate and/or ammonium bicarbonate which is returned as such to the first absorption stage, and the waste gas containing carbon dioxide is brought into contact with a sulphuric acid of medium concentration containing from 0.1-5% by weight, preferably from 0.2 to 1.5% by weight of nitric acid before the carbon dioxide is introduced into the second absorption stage.