Iodine monobromide is an interhalogen compound with the formula IBr. It is a dark red solid that melts near room temperature. Like iodine monochloride, IBr is used in some types of iodometry. It serves as a source of I<sup>+</sup>. Its Lewis acid properties are compared with those of ICl and I<sub>2</sub> in the ECW model. It can form CT adducts with Lewis donors.
Iodine monobromide is formed when iodine and bromine are combined in a chemical reaction:.