Abstract: A portable fire extinguishing device capable of suppressing a fire in a room or other enclosed area comprises a housing containing a pyrotechnic composition and a delay fuze. Upon initiation, the pyrotechnic composition burns and generates combustion byproducts that include an inorganic halogen compound that is dispersed as a aerosol of fine particles, or a gas that rapidly condenses into an aerosol of fine particles, the particle size of which is so small that the free-fall velocity of the particles is less than the average air currents in the room. Accordingly, the fire suppression aerosol remains suspended for several hours to act as a fire suppressant and because of its persistence will seek out and suppress even hidden fires.