Bromine monochloride

Bromine monochloride, also called bromine(I) chloride, bromochloride, and bromine chloride, is an interhalogen inorganic compound with chemical formula BrCl. It is an unstable red-brown gas with boiling point 5°C and melting point -66 °C. Its CAS number is 13863-41-7 and its EINECS number is 237-601-4. It is a strong oxidizing agent.

Bromine monochloride is used in analytical chemistry in determining low levels of mercury, to quantitatively oxidize mercury in the sample to Hg(II) state.

Bromine monochloride is used as a biocide, specifically as an algaecide, fungicide, and disinfectant, namely in industrial recirculating cooling water systems. It is the active ingredient of eg. Stabrom 909 biocide. 

Addition of bromine monochloride is used in some types of Li-SO2 batteries to increase voltage and energy density.