Using ultra low energy SIMS ion beams of oxygen and nitrogen, the very near surface region of an O-16 annealed La0.8Sr0.2MnO3 pellet has been depth profiled in order to investigate the surface layer composition and to determine any perturbing ion beam-target interactions. By ratioing the measured cation species, the results indicate that only Sr segregation at the near surface can be clearly identified, and no separate oxide layer was present on the top surface. By monitoring the build up of the altered layer associated with SIMS depth profiling, it was observed that the depth at which the altered layer was fully fon-ncd was deeper than the expected projected range, R, of the ion beam. These results confirm Sr excess in the near surface, which will have an effect on the vacancy concentration and therefore the surface exchange coefficient, k. (C) 2008 Elsevier B.V. All rights reserved.