Electron-induced ion desorption from platinum, platinum-iridium, and molybdenum is studied by means of a quadrupole mass spectrometer, in order to determine its influence on the measurement of pressure by ionization gauges. Adsorbed species studied were H, H2O, CO, and O2. Ion yields, which were obtained under various conditions, are given. Interaction between coadsorbed species caused changes in the electronic desorption probabilities from the values observed for the separately adsorbed species. Suggestions are given for proper operation of ionization gauges in order to minimize ion desorption.