The stress corrosion cracking (SCC) susceptibility of several Fe-Ni-Cr-Mo alloys, which are candidate materials for high-level radioactive waste containers, was evaluated using slow strain rate and fracture mechanics testing. Slow strain rate tests of type 316L stainless steel (SS) and alloy 825 were performed in hot, concentrated chloride solutions (6.2 to 14.0 molal Cl-). SCC of type 316L SS was observed at chloride concentrations equal to or greater than 7.2 molal and temperatures above 95°C, whereas, alloy 825 experienced SCC only in a 14.0 molal Cl− solution at 120 °C. In both materials, SCC does not occur at potentials below the repassivation potential for pitting corrosion (Erp). In fracture mechanics tests using wedge-loaded specimens, alloy 22 was found to be resistant to SCC when tested in 14.0 molal Cl- solutions at 110°C. On the contrary, crack growth was observed in type 316L SS specimens exposed to concentrated chloride solutions at potentials above the Erp. These results suggest that Erp constitutes a lower limit for the critical potential for SCC that can be used for assessing material performance.