Sets of tiny probes made of graphite (5 mm diam. and 1 mm thick) were exposed to hydrogen as well as deuterium plasma of the tokamak discharges at different radial positions. The probes were highly polished and had previously been annealed in vacuum to about 900°C. They were kept isolated from the wall. Each set was irradiated by the plasma for only a few shots. The probes were either kept floating or biased to −45 or +45 V. The corresponding floating potential or the net current to each probe was measured as a function of time during the pulsed discharge. Subsequently, the probes were removed from the ASDEX to the laboratory under argon and placed in the SIMS device UMPA. The mass spectra and depth profiles of different isotopes were obtained by using Ar + ions of 2.4 keV and 1–2 nA. A number of quantities can now be determined from these measurements. The data thus obtained are interpreted in the light of plasma diagnostics, plasma parameters, and SIMS as well as plasma-surface interaction including impurities and recycling. The results are presented and a general discussion is given. Finally, conclusions are drawn.