The molecule adopts a square pyramidal structure with C4v symmetry,[1] as confirmed by its high-resolution 19F NMR spectrum.

[5] In a highly exothermic reaction, ClF5 reacts with water to produce chloryl fluoride and hydrogen fluoride:[7] It is also a strong fluorinating agent.

At room temperature it reacts readily with all elements (including otherwise "inert" elements like platinum and gold) except noble gases, nitrogen, oxygen and fluorine.

As a propellant, it has a higher maximum specific impulse than ClF3, but with the same difficulties in handling.

[4] Due to the hazardous nature of chlorine pentafluoride and the large amounts of hydrogen fluoride in the exhaust, it has yet to be used in a large scale rocket propulsion system.