A thermal inkjet printhead with heater elements formed from a self passivating transition metal nitride, but it oxidizes readily. By introducing an additive that allows the metal nitride to self passivate, the heater element forms a surface oxide layer, where the oxide has a low diffusion coefficient for oxygen so as to provide a barrier to further oxidation. With enhanced oxidation resistance, coatings to protect the heater from oxidative failure become unnecessary and the energy needed to form a bubble is reduced.