Chlorine monofluoride is a volatile interhalogen compound with the chemical formula ClF.

[1] The molecular structure in the gas phase was determined by microwave spectroscopy; the bond length is re = 1.628341(4) Å.

In its molecular packing it shows very short intermolecular Cl···Cl contacts of 3.070(1) Å between neighboring molecules.

[3] Chlorine monofluoride is a versatile fluorinating agent, converting metals and non-metals to their fluorides and releasing Cl2 in the process.

For example, it adds fluorine and chlorine to the carbon of carbon monoxide, yielding carbonyl chloride fluoride, an intermediate between phosgene and carbonyl fluoride.