Isotope Exchange/Depth Profiling (IEDP) using Secondary Ion Mass Spectrometry (SIMS) has been used to determine the oxygen tracer diffusion and surface exchange coefficients of (100) oriented 9.5 mol% yttria stabilised zirconia single crystals. Exchange experiments performed with molecular oxygen are compared with the exchange using an oxygen plasma. The surface exchange coefficient for specimens in a plasma is up to 100 times higher compared to measurements with normal molecular oxygen. For the exchange experiments we used an inductively coupled radio frequency (rf) oxygen plasma with a maximum radio frequency power of 250 W Double probe measurements and optical emission spectrometry are used for the characterisation of the plasma. The measured electron temperatures are within the range of 5-12 eV. (C) 2003 Elsevier B.V. All rights reserved.