An analytical and experimental investigation of heat transfer to, and the resulting temperature distribution in, a metal-cutting tool during orthogonal cutting is described. A rectangular parallelepiped-shaped tool is postulated and a product solution developed for the temperature distribution under the conditions of a continuous uniform release of heat over the tool-chip contact area and heat loss from each side arbitrarily specified. To test the validity of this solution two high-speed lathe tools with 0-deg and 15-deg back-rake angles were uniquely instrumented with thermocouples located in the tool bodies at selected distances from the cutting edges. Representative temperature records obtained during dry orthogonal cutting of SAE 1020 steel with these tools are presented. Extrapolation of temperature measurements to the center of the tool-chip contact area gave values for the average tool-chip interface temperatures which agree quite closely with results of other investigators. Average heat rates to the tools are determined and the applicability of the product solution is discussed.