Flame hardening method and apparatus for tempering gear teeth and the like which comprises quench means for rapidly cooling selected ones of the gear teeth to a temperature which avoids the formation of decomposition products, and a heat source spaced from the quench means for raising the temperature of selected ones of the gear teeth to a value which promotes the formation of an austenitic structure.Mount means rotatably support the gear with selected ones of the circumferentially extending teeth being placed in heat transfer relationship with the heat source and the quench.Index means rotate the gear an amount which moves one gear tooth from the heat source to the quench means in a manner whereby all of the teeth of the gear must be treated one time before any tooth can be treated a second time.