A study comparing the surface concentration of barium on both an impregnated tungsten cathode surface and M-type cathode surface was made to determine whether the higher electron emission capability of the latter can be attributed to a higher average surface barium concentration. Relative quantitative data was obtained by the use of a computerized Auger microprobe spectrometer on the surface of the cathode, half of whose area was M-type, the other half being the tungsten impregnated type. The results indicate that both cathode surfaces have equivalent barium concentrations and that they are approximately equal to a barium monolayer after 3000 h of cathode life.