Phosgene, also called carbonyl chloride (COCl₂), is a colorless, reactive gas, hydrolyzed by water, made by catalytic combination of carbon monoxide and chlorine, and used to make resins and dyes. Highly toxic, it was used as a poison gas in World War I. Boiling point 8.2°C (46.8°F), melting point –118°C (–180.5°F).