Mixed oxides of nitrogen


Mixed oxides of nitrogen (MON) are solutions of nitric oxide (NO) in dinitrogen tetroxide/nitrogen dioxide (N2O4 and NO2). It may be used as an oxidizing agent in rocket propulsion systems.[1] A broad range of compositions is available, and can be denoted as MONi, where i represents the percentage of nitric oxide in the mixture (e.g. MON3 contains 3% nitric oxide, MON25 25% nitric oxide). An upper limit is MON40 (40% by weight). In Europe MON 1.3 is mostly used for rocket propulsion systems, while NASA seems to prefer MON 3. A higher percentage of NO decreases the corrosiveness and oxidation potential of the liquid, but increases costs.

The addition of nitric oxide also reduces the freezing point to a more desirable temperature. The freezing point of pure nitrogen tetroxide is −9 °C (16 °F), while MON3 is −15 °C (5 °F) and MON25 is −55 °C (−67 °F).[2]


  1. ^ Wright, Alfred C. (February 1977). USAF Propellant Handbooks. Nitric Acid/Nitrogen Tetroxide Oxidizers. Volume II. USAF (Report). Defense Technical Information Center. AFRPL-TR-76-76 (DTIC Accession Number ADA036741). Archived from the original on March 3, 2016. Retrieved 14 April 2013.
  2. ^ Robert A. Braeunig (2008). "Rocket Propellants". Rocket and Space Technology. Archived from the original on 21 May 2013. Retrieved 14 April 2013.