A study of wrought and cast Co-base and Fe-base alloys was conducted with the object of development of better high-temperature alloys having a minimum strategic alloy content. An alloy containing 10% Ni, 10% Cr, 10% W, 5% Mo, and 1% Nb + Ta was outstanding in rupture properties for the wrought Co-base alloys at 1500 to 1700 deg F. An 18% Mn, 12% Cr, 3% Mo, 0.8% V alloy had a good combination of properties for application at 1200 deg F for the wrought Febase alloys. Thermal shock properties were best for the cast alloys containing the highest Co. No correlation was apparent between thermal shock characteristics and other commonly measured properties. (auth)