The followinguses for caesium are gathered from a number of sources as well as from anecdotal comments. I would be delighted to receive corrections as well as additionalreferenced uses.

Caesium (cesium in USA) has relatively few uses and is not often encountered. Some uses include:

• used as a catalyst in the hydrogenation of a few organic compounds
• the metal can be used in ion propulsion systems. Although not usable in the earth's atmosphere, 1 kg of caesium in outer space could propel a vehicle 140 times as far as the burning of the same amount of any known liquid or solid. It is more efficient than rubidium.
• used in atomic clocks
• because of its high oxygen affinity, the metal is used as a "getter" in electron tubes
• used in photoelectric cells and vacuum tubes
• IR lamps