Sliding experiments using mainly the metals zinc, copper, titanium, and 1020 steel were carried out on a pin-on-disk friction apparatus incorporated in a metallurgical furnace. At room temperatures the results with steel, but not with the other metals, depended markedly on the atmospheric moisture content. As temperatures were raised to 400 C the friction and wear rate of the steel reached a maximum at 100 C and then diminished, while with the other metals the friction remained constant and the wear rate increased. These and other results are discussed in terms of the W/p ratio for the metals, W being the surface energy and p the hardness. It is postulated that materials with low W/p ratios should have favorable friction properties at high temperatures.