A study has been made of the inhibition of emission from barium‐activated tungsten dispenser cathodes and adjoining molybdenum electrodes which can be produced by carburization. X‐ray diffraction and metallographic techniques have been employed coupled with emission measurements as a function of time, temperature, and arrival rate of Ba+BaO. Performance characteristics including the extent of the emission suppression and its time dependence are presented. It is concluded that the emission inhibition results from greatly reduced activator coverage of the surface of the carbide relative to that of the metal owing to much weaker adsorption forces. Return of emission coincides with disappearance of the carbide layer from the surface via diffusion.