Sliding experiments from—195 to +200 C are reported for metals lubricated with thin films of hydrocarbons, fatty acids, and synthetic lubricants in helium and air. For copper and iron pairs lubricated with pure organic compounds, a marked rise in friction and wear is found to occur at the melting point of the film material. From just below the melting point down to —195 C, there is an increase in friction but negligible wear, indicating increased shear strength of the solid film. This is substantiated by contact resistance measurements.