Abstract: A nickel-based superalloy is provided which is resistant to deterioration in hydrogen at high operating temperatures and pressures, and which thus can be used in hydrogen-fueled spacecraft such as the Space Shuttle. The superalloy is characterized by a two-phase microstructure and consists of a gamma-prime precipitated phase in a gamma matrix. The gamma matrix phase is a primary solid solution and the gamma precipitated phase will be an intermetallic compound of the type A.sub.3 B, such as nickel aluminide or titanide. Both phases are coherent, ordered, and compatible, and thus will retain most of their strength at elevated temperatures. The alloy consists essentially of (by weight):______________________________________ Ni 50-60% Cr 10-20% Al 2-6% Co 2-5% Ti 3-8% W 5-12% Mo 5-10% Nb 1-3% ______________________________________wherein the ratio W/MO is approximately equal to 1, and Ti/Al ranges from about 1 to about 2.