Heat generation and surface temperature rise are the main parameters controlling friction and wear of polymers, while certain transitions in sliding behavior often are difficultly related to intrinsic polymer transition temperatures. The sliding temperature cannot be accurately measured through physical limitations in the contact interface, and different calculation methods are available. Some temperature models are reviewed and applied to the reciprocating sliding of polyimide (PI) and polyethylene terephthalate against a steel counterface. The bulk temperature and asperity flash temperature models cannot explain transitions in friction and wear for polymers under reciprocating sliding. The bulk temperature model provides too low temperatures, representing a long-range temperature, while the asperity flash temperature model provides too high temperatures, not considering visco-elastic deformation of the polymer surface. An experimental model for the maximum polymer surface temperature T* under reciprocating sliding is developed, considering the environmental temperature, gradual heating of the steel counterface, and additional heating of the polymer surface. The proposed temperature model is analytically validated by differential thermal analysis and thermogravimetric analysis. Transitions in tribological behavior are controlled by the maximum polymer surface temperature T*, coinciding with an endotherm reaction (PIs) or a glass transition and melting (polyethylene terephthalate).