Austenitic Alloy C-22 has been proposed to be a structural material in sulfuric acid decomposition process related to a thermochemical cycle associated with hydrogen generation using nuclear heat. In view of unusually high operating temperatures associated with this cycle, tensile properties of this alloy have been determined as functions of temperature and strain rate. A mechanistic understanding of tensile deformation based on activation energy, work-hardening index and dislocation density has been presented. Furthermore, the results of fractographic evaluations of the tested specimens have been included. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.