Abstract Phosgene oxime (CAS 1794-86-1; CX) is a compound that has no known uses other than as a weapon of warfare. Of increasing concern is the potential use of phosgene oxime as a chemical terrorist weapon. It is relatively easy to synthesize and can exist in pure form as a white powder or yellowish powder depending on the impurities that are present. It is volatile, can exist as a liquid at room temperature, and has a high vapor pressure. The ability of phosgene oxime to mix with water and other solvents results in its hydrolysis and is particularly unstable in alkali environments. One of the major concerns of phosgene oxime use as a chemical weapon is its ability to be mixed with other agents, with phosgene oxime increasing the susceptibility of the victim to the other agents by damaging the victim’s skin, lungs, and mucosal lining. Little can be done to protect against phosgene oxime exposure, and in many cases victims will actually remove their protective clothing, further exposing the victim to the actions of phosgene oxime. Treatment for phosgene oxime exposure simply involves removing the victim from the source(s) of the irritation and treating symptomology.