Just one month after the discovery of neon, xenon was discovered in July 1898. The discovery of krypton and neon was based on the new technology of refrigeration. Liquefying large quantities of air made it possible to produce xenon in sufficient quantities for separation and identification. The separation was possible because xenon is more dense and has a much higher critical temperature than the other two gases.

Xenon is a heavy (i.e. 4.5 times heavier than air), unreactive stable gas occurring in air in trace percentages. It is one of the noble gases. Today, xenon is recovered on a commercial scale by the fractional distillation of liquid air.

In 1962, a sample of xenon combined with an ion of platinum and fluorine to produce the first noble gas compound. Now, xenon is known to combine with fluorine, oxygen, cesium, and alkali metals to form the corresponding fluorides, oxides and salts. All xenon compounds are toxic, although the gas itself is not.

Xenon has been used as an anesthetic. It is the most popular gas used in strobe lamps and in high speed electronic flash bulbs used in photography. Electrical excitation of xenon atoms produces a brilliant white light. Some of its compounds have limited application as oxidizing agents . Xenon gas also has applications in modern nuclear power reactors.