Hydrogen concentrations and hydrogen release activation energies from trap sites were investigated for austenitic stainless steels by thermal desorption spectroscopy. It was found that hydrogen concentrations could be determined by the peak areas of the desorption specrta. A spectrum could be separated into four peaks given by Gaussian distribution profiles. Their activation energies were calculated to be 73, 87, 96 and 180 kJ/mol. The peak with the highest activation energy seemed to represent hydrogen coming from the grain boundaries, while the other three peaks were related to hydrogen coming from chromium carbide precipitates.