Application of lead-based liquid alloys or liquid tin to thermal energy conversion or storage opens the avenue to compact in design, highly efficient components in the high-temperature section of respective plants, however, at the cost of increased corrosion of metallic materials of construction, namely nickel-containing steels or nickel-based alloys. Experimental studies identify selective leaching of constituent parts, especially nickel, as an intermediate stage of complete dissolution, with the near-surface depletion zone originating in the solid alloys being dependent on the alloy composition, the liquid metal and temperature. If the oxygen content in the liquid allows, formation of solid oxides at least alters but may even suppress the leaching process, i.e. change the corrosion mode, just as intermetallic compounds forming in the presence of liquid tin. The observations evaluated with respect to fundamental mechanisms stem from experiments in lead-based alloys and liquid tin at 450–750 and 500–1000 °C, respectively.