The current concept for the Westinghouse LMFBR steam generator is of the single-tube once-through type and incorporates both the evaporator and superheater in a common containment. Selection of a single-tube material that will operate reliably within design limits of the steam generator inevitably requires some compromise. The material must have adequate strength at high temperatures; it must be compatible with sodium and water environments over the range of operating temperatures; it must be resistant to chloride-and hydroxide-induced stress corrosion cracking and to sodium-water reactions. Incoloy-800 of specially controlled composition was selected as the tubing alloy for the Westinghouse LMFBR steam generator after several reviews and tradeoff studies, and meets all requirements, apart from stress corrosion resistance, without compromise. In the area of stress corrosion resistance it is considered superior to the austenitic 300 series stainless steels and, with suitable water chemistry control, is expected to perform reliably.