Corrosion characteristics of materials in Pb–Bi under transient temperature conditions in the range 550–800 °C have been investigated. Two cases of transient temperature conditions were carried out. For the case-1, the specimens were immersed in Pb–Bi at 550 °C for 12 h and then the temperature was increased up to 800 °C and kept there for 12 h. For the case-2, the specimens were immersed in Pb–Bi at 550 °C for around 500 h and then the temperature was increased up to 800 °C and kept there for 15 h. The tested materials were surface coated steels of Al-SUS304-sputtering-coated HCM12A and SUS316, high chromium steels of HCM12A, Recloy10 and SUS430, a refractory metal of molybdenum, and ceramics of SiC and Ti3SiC2. The results showed that there was no trace of any corrosion attack mechanisms of Pb–Bi into the Al-SUS304-sputtering-coated steels, the refractory metal, and the ceramics found, for all transient temperature conditions cases. On the other hand, corrosion attack mechanism of Pb–Bi was found for high chromium steels specimens in all cases.