Safety Services


Nitrogen Triiodide (NI3)​

Nitrogen triiodide is the inorganic compound with the formula NI3. It is an extremely sensitive contact explosive.

Why this substance is hazardous?​

  • Nitrogen triiodide is an inorganic compound which is a contact explosive, that reacts violently to exposure to a relatively small amount of energy including friction, pressure, sound, light and α (alpha) radiation. The explosion is usually a loud, sharp sound.​
  • The explosion releases a purple cloud of iodine vapour, which is an irritant and on inhalation can adversely affect the upper and lower respiratory system. ​
  • The immediate effect of exposure to iodine vapour may be the excessive flowing of tears, tightness in the chest, sore throat and headaches.​


There are currently no industrial uses for nitrogen triiodide, but the substance is often used as an example of a contact explosive. Demonstrations can take ammonia (NH3) solution and pour it on to iodine. The iodine replaces the hydrogen for some of the molecules making an adduct of NH3 and NI3. The instability comes from the crowding of 3 iodine molecules on the nitrogen atom, the explosive reaction is 2NI3(s) → N2(g) + 3I2(g).​

Recommended control measures​

This is a controlled chemical (explosive) – see information on standards for all controlled chemicals.

Minimise the risk of exposure

UCL (and other teaching institutes) can make and use 0.5 g of explosive in one location for demonstration purposes, without additional licences. Do not use amounts that will exceed this limit.​


Do not store​


Preparation must be done in a fume cupboard, eye protection and gloves must be worn when handling chemicals. Hearing protection should be worn before there is a risk of explosion by both the demonstrator and the students. If leaving to dry overnight, warning signs must be left and access restricted to the location​

Health surveillance ​

WEL STEL = 0.1 ppm or 1.1 mg/m3  There must be a system in place to ensure the WELs are not reached or exceeded.​

Chemical safety library

> Read more about control measures for chemicals in our chemical safety library 

Last updated: Tuesday, June 23, 2020