Sputtering of CeF3and LaF3surfaces by singly charged rare gas ions (Ar+, He+, Xe+) with impact energies between 100 and 1500 eV has been performed. The emission of Ce+, La+and F+was measured by quadrupole mass spectrometer. The yield of Ce+, La+decreases with decreasing impact energies; under ∼160 eV this decrease becomes very rapid compared with the decrease of F+yield. For He+bombardment a higher yield of F+was observed than for Ar+bombardment. The F+yield for Xe+bombardment is even lower than for Ar+. Therefore an electronic effect has to be assumed as a cause of the F+emission enhancement as in the case of LiF. The quantitative differences between the data on LaF3, CeF3and on LiF have been explained using our results on valence band measurements of rare earth trifluorides by XPS method.