INCONEL alloy 625® fuel-cladding material has been corrosion-tested under heat-transfer conditions at metal temperatures up to 1500°F (816°C) in specially designed out-of-pile superheat facilities. The hydrogen and oxygen contents of the steam were controlled to simulate those found in boiling-water-reactor systems. The corrosion data from the 3600-h heat-transfer tests indicated good corrosion resistance up to the 1500°F metal temperature tested. A compositionally changed layer developed at the metal-oxide interface that appeared to reach a maximum depth at the higher temperatures. The heat-transfer test data indicated that except for a small buildup of oxide during the initial nonlinear transient corrosion period, most of the oxide formed in corrosion was carried downstream by the superheated steam. The uniform corrosion experienced by the INCONEL-625 when exposed isothermally to 1050 and 1150°F (566 and 621°C) for 10 000 h indicates an initially high-corrosion rate that decreases to a lower constant rate within the first 1000 h. A small proportion of the total oxide formed was gradually lost to the system.