cw operation of a chemical oxygen‐iodine laser (COIL) using ICl as a source of atomic iodine at powers approaching 120 W is reported. The vapor pressure of ICl is higher than the vapor pressure of the more conventional I2fuel usually used in COIL. More iodine can therefore be delivered to the laser gas stream using ICl than can be delivered using I2. This concentration increase is advantageous for low‐temperature operation at high partial pressures of the atomic iodine source.