Disulfur decafluoride is a colorless liquid. It has no odor. It is very toxic. It disproportionates to sulfur hexafluoride and sulfur tetrafluoride when heated. It reacts with sulfur dioxide. It also can react with chlorine, bromine, and ammonia. It is more toxic than phosgene.
It was thought of as a poison gas in World War II, but it was never used. It has almost no uses.