Molybdenum alloys with good strength properties at elevated temperatures were produced by the powder metallurgical internal oxidation method previously applied to tungsten and known as oxyreaction strengthening. Commercial molybdenum powders were blended with 0 to 10 pct of a reactive powder, zrmo2. The effects of composition, blending procedure, and sintering conditions on strength properties at elevated temperatures were studied. Strengthening was attributed to zirconium in solid solution with molybdenum and to the presence of submicrometer particles of zro2. Several alloys had tensile strength and stress-rupture properties comparable with those of the best commercial alloys. The maximum tensile strengths obtained were 92 kpsi at 1,200 deg c and 53 kpsi at 1,316 deg c. The maximum stress-rupture life at 30 kpsi and 1,200 deg c was 145 hours.