Secondary ion mass spectrometry (SIMS) is used to measure quantitatively the thickness of thin (6-160 Å) polyperfluoroether films on silicon and gold surfaces. Linear relationship between ellipsometrically measured thicknesses and integrated SIMS signals is demonstrated. Time dependence of SIMS signals indicates that the polymeric films have a uniform thickness down to the thinnest layers studied. In the lower limit, the fluorocarbon polymers have extended, flat conformation due to polymer-substrate interactions. Sputtering yield and effective sputtering depth of oxygen ions are determined for these liquid polymers. It is also shown that organic adsorbates reside between the solid surface and the low surface tension fluorocarbon films. © 1991.