Four sets of experiments were conducted in order to find the most efficient extinguishing agent for use on fires of metal dusts such as aluminum and magnesium. Parameters considered included time before application of agent, ratio of applied agent to metal dust, time to extinguishment, and active versus inert chemical composiotion of agents. A 30% active, 70% inert mixture of zinc stearate and sand was found to be an effective and economical extinguishing agent for metal dust fires.