The stress corrosion cracking (SCC) susceptibility of Alloy 600 MA, Alloy 600 TT, Alloy 800, and Alloy 690 TT were investigated in a deaerated 0.01 M solution of sodium tetrathionate using reverse u-bend test samples at 340 °C. The results showed that SCC occurred in all alloys, excluding Alloy 690 TT. The SCC susceptibility of the alloys increased in the following order: Alloy 690 TT, Alloy 800, Alloy 600 TT, and Alloy 600 MA. The SCC susceptibility decreased with an increase in the chromium content of the alloys. The results of the deposits and spectra taken from an energy dispersive X-ray system confirmed the existence of a reduced sulfur causing SCC.