Like hot black oxide, mid-temperature black oxide converts the surface of the metal to magnetite (FeO). However, mid-temperature black oxide blackens at a temperature of , significantly less than hot black oxide. This is advantageous because it is below the solution's boiling point, meaning there are no caustic fumes produced.
Since mid-temperature black oxide is most comparable to hot black oxide, it also can meet the military specification MIL-DTL-13924, as well as AMS 2485.