Bromotrifluoromethane, commonly known as Halon 1301, R13B1,Halon 13B1 or BTM, is an organic halide with the chemical formula C Br F₃. It is used for fire suppression and refrigeration. Human exposure to Halon 1301 can be toxic, affecting the central nervous system and other bodily functions. Additionally, it is known to contribute to the depletion of Earth's atmospheric ozone layer when released. As such Halon's use as a refrigerant has been virtually eliminated and alternatives are being used increasingly for fire suppression.

Halon 1301 was developed in a joint venture between the U.S. Army and DuPont in 1954, and introduced as an effective gaseous fire suppression fixed systems agent in the 1960s, and was used around valuable materials, such as aircraft, mainframe computers, and telecommunication switching centers, usually in total flooding systems. It was also widely used in the maritime industry to add a third level of protection should the main and emergency fire pumps become inoperable or ineffective. Halon 1301 was never widely used in portables outside military and spacecraft applications, due to its limited range, and invisible discharge. It does not produce the characteristic white cloud like CO₂ and is difficult to direct when fighting large fires. Halon 1301 is ideal for armored vehicles and spacecraft, however, because it produces less toxic by-products than does Halon 1211, which is critical for combat or space conditions where a compartment may not be able to be ventilated immediately. Halon 1301 is widely used by the U.S. Military and NASA in a 2-3/4 lb portable extinguisher with a sealed, disposable cylinder for quick recharging. Other agents such as CO₂ and E-36 Cryotech wet chemical are largely replacing halon 1301, however, due to environmental concerns. Civilian models in 2-3/4, 3, and 4 lb sizes were also made.

It is considered good practice to avoid all unnecessary exposure to Halon 1301, and to limit exposures to concentrations of 7 percent and below to 15 minutes. Exposure to Halon 1301 in the 5 to 7 percent range produces little, if any, noticeable effect. At levels between 7 and 10 percent, mild central nervous system effects such as dizziness and tingling in the extremities have been reported. In practice, the operators of many Halon 1301 total flooding systems evacuate the space on impending agent discharge.

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