A portable automatic fire extinguisher having a tubular member mounted exteriorly of the extinguisher housing and containing a fluid that expands significantly in response to an abnormal ambient temperature condition. A bellows is surrounded by the fluid and is displaced during fluid expansion. A push rod is connected to the bellows at a first end of the rod while the opposite end mounts a valve. When the bellows is displaced, the push rod is similarly moved thus causing the valve to open and free a stored reagent for mixing with a second reagent which results in the formation of a fire-extinguishing liquid. A discharge tube is disposed in the extinguisher housing and has a nozzle end extending outwardly from the housing so that the extinguishing fluid can be discharged omnidirectionally.