[en] The stress corrosion cracking of sensitized Alloy 600 was investigated in aerated solutions of sodium thiosulfate generally containing 1.3% boric acid. The aim of the investigation, among others, was to determine the existence, if any, of a threshold level of sulfur, and lithium to sulfur ratio governing the SCC. Specimens were first solution annealed at 1135⁰C for 45 minutes, water quenched, and then sensitized at 621⁰C for 18 hours. Reverse U-bends were tested at room temperature, whereas slow strain rate and constant load tests were performed at 80⁰C. All tests were performed in solutions open to the atmosphere. The results indicate that in the borated thiosulfate solution containing 7 ppM sulfur, 5 ppM lithium as lithium hydroxide is sufficient to inhibit SCC in U-bends. The occurrence of inhibition seems to correlate to the rapid increase of pH and conductivity of the solution as a result of the lithium hydroxide addition. In the slow strain rate tests in the borated solution containing 0.7 ppM lithium as lithium hydroxide, significant stress corrosion cracking is observed at a sulfur level of 30 ppb, i.e., a lithium to sulfur ratio of 23. In a parallel test in 30 ppb sulfur level but without any lithium hydroxide, the stress corrosion cracking is more severe than that in the lithiated environment, thus implying that lithium hydroxide plays some role in the stress corrosion cracking inhibition