Pyrophoric reagents are substances that will ignite spontaneously when exposed to air. Very often, this is due to a reaction with the water in the air. Thus pyrophoric reagents should be used only under inert atmospheres, such as in a glovebox filled with an inert gas such as argon or nitrogen. Often, pyrophorics will be sold as solutions already dissolved in a solvent so that they do not tend to create fires so easily. Some of the more mild pyrophoric substances can be handled in the air, but caution needs to be exercised to flush air out of the container before storing them for an extended period of time. They also must be disposed of with caution, or they might accidentally set the wastebucket on fire!

Perhaps not surprisingly, pyrophoric materials can be useful for starting fires in a controlled manner. Pyrophoric materials are present in the spark-generating mechanisms in lighters and some firearms.