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Compression tests were used to simulate simple deformation paths within the upper a-range of Zircaloy-4 (i.e. 500°C-750°C). The mechanical behaviour reveals two different domains : at low temperatures and large strain rates, strain hardening takes place before flow softening, whereas this first stage disappears at lower flow stress levels. Strain rate sensitivity and activation energy were determined for both domains. Dynamic recrystallization was investigated using the Electron BackScattering Diffraction (EBSD) technique. It appears that the mechanism involved here is continuous dynamic recrystallization (CDRX), based on the increasing misorientation of subgrain boundaries and their progressive transformation into large angle boundaries. At low strains (e £ 0.3), CDRX kinetics are similar whatever the deformation conditions, while higher temperatures and lower strain rates promote recrystallization at large strains.