A “generalized” thermal analysis is described to estimate the flash temperature during sliding when both surfaces are of more or less equal roughness or one surface is substantially smoother than the other. High- and low-speed cases are considered. The basic model includes surface-topography statistics, frictional conditions, and mechanical and thermal parameters. Temperature history during the life of an individual asperity contact is calculated, from which average temperatures of an asperity contact are calculated. Thermal interaction of neighboring asperity contacts is considered. Then, an analysis is presented to show how individual asperity temperatures should be averaged. Temperature variations perpendicular to the sliding surfaces are also analyzed. Throughout the analysis, closed-form equations are developed, which can be conveniently used in the design of any sliding interface. © 1987 by ASME.