Tests of refractory coatings of molybdenum and niobium on Type 316 stainless steel were performed in flowing sodium for 1000 hours at 649 degree C (1200 degree F). Specimens coated with niobium lost weight because of spalling. Molybdenum coated specimens showed a small weight gain which was the result of iron deposition from the corrosion loop surfaces. The molybdenum coating remained intact during thermal shock tests consisting of more than 100 cycles from 627 degree C (1160 degree F) to 427 degree C (800 degree F).