The small punch (SP) test is a novel technique that uses a relatively small volume of material, to enable a measure of load versus deflection to determine the mechanical behaviour of the alloy. This study aims to investigate the mechanical properties of Zircaloy-4 (Zr-4) alloy which will be used for construction of many of the core components in ANSTO’s replacement research reactor at Lucas Heights in Australia. The Zr-4 alloy was hydrided under different conditions to simulate the radiation-induced reduction in fracture toughness over the service life of the reactor. The SP test was applied to determine the deformation and fracture behaviour of the hydrided materials. It was found that as the hydride formation increased, the equivalent fracture strain (eqf) of the alloy decreased to lower values.