Mass spectrometric techniques have been utilized to study sublimation characteristics of materials used in electron tubes. Exploratory experiments and methods are described. Preliminary results concerning general processes induced by heat and by electron bombardment are discussed. Photographs are shown of mass spectrometer traces which demonstrate the effects described. Phenomena noted include (1) the inefficiency of electron bombardment for producing material transport from solids, (2) the thermal evaporation of alkali metal atoms and ions from bare nickel alloys, but no such evaporation from oxide cathodes formed on the same materials, (3) the complex thermal evaporation of oxide cathode constituents, (4) absence of positive ion evaporation from oxide cathodes, (5) the confirmation of mechanisms for negative ion formation in vacuum systems, and (6) the liberation of molecular oxygen from oxide cathodes which increases with electron emission drawn.