Abstract: Nitrites having minimum amounts of the corresponding nitrates are produced by rapidly quenching a gaseous mixture of nitrogen oxides to a temperature less than 120.degree. C. by dispersing the gas into intimate contact with and under the surface of an aqueous solution of a base, for example sodium hydroxide, which solution is maintained at a temperature in the range 30.degree.-120.degree. C., and thereafter continuing absorption of the gas into the base until at least 90% of the nitrogen oxides originally present are removed from the gaseous mixture. The gaseous mixture is maintained above its dew point until the aforesaid dispersion is effected, and a coating of the aqueous solution, preferably in the form of a foam, is maintained on the cold walls to minimize condensation of water and consequent nitrate formation.