Tests were conducted in the Lubrication Laboratory of the Virginia Polytechnic Institute to study the effect of several metals on the deterioration of steam-turbine oils. A special test apparatus was constructed and three commercial turbine oils were tested in the presence of 14 different metal and metal combination. Included in this group of metals were five bearing metals, several metals now extensively used in turbine lubricating systems, and several metals that are not at present used in turbine oiling systems. Oxidation of the oils was accomplished by heating the oil in glass containers at 275°F for 200 hours, in the presence of the metals. The oil samples were then subjected to laboratory inspections to determine the extent of oxidation. It was found that in the case of oil A copper, lead and the copper-lead combination were increasingly effective in increasing the viscosity and acidity. Brass, copper, and copper-lead were increasingly effective in promoting sludge formation. With oil B copper, lead, and the copper-lead combination were increasingly effective in promoting sludge formation and increasing the viscosity. Steel, lead and the copper-lead combination were increasingly effective in producing acidity. Copper, metal No. 9, and the copper-lead combination were increasingly effective in increasing the viscosity of oil C. Copper, metal Ho. 5, and copper-lead produced acidity in increasing amounts. Aluminum, zinc, and cooper were increasingly effective in promoting sludge formation. Tin showed the least effect on solidity in the case of all three oil. It caused the lowest sludge formation with oils A and B and was low with oil C. The viscosity of oil A was least affected by metal No. 6, of oil B by metal No. 8, end of oil C by steel. / Master of Science