Abstract: A process for the manufacture of nitric acid comprises contacting a mixture of starting gas, containing oxygen, nitrogen oxides and, possibly water, this mixture being previously cooled, oxidized and, optionally dried, with cooled nitric acid aqueous solution to provide a solution of nitrogen oxides in nitric acid aqueous solution, consisting fundamentally in that the said solution is reacted according to the reaction:2 NO.sub.2 (and/or N.sub.2 O.sub.4)+1/2 O.sub.2 +H.sub.2 O.fwdarw.2 HNO.sub.3with the air previously contacted with the solution of nitrogen oxides in the highly concentrated nitric acid resulting from the said reaction, so as to rid the said highly concentrated acid of the nitrogen oxides dissolved therein.