This paper addresses modeling of the tool temperature distribution in self-propelled rotary tool (SPRT) machining of hardened steels. Since tool life is significantly influenced by cutting temperatures, a model is developed to analyze the heat transfer and temperature distribution in rotary tool turning of hardened 52100 steel (58 HRC). The model is based on the moving heat source theory of conduction and employs the finite element method (FEM) for its solution. The model is experimentally verified through measurements of the cutting tool temperature distribution using an infrared camera under different cutting conditions. Finally, both rotary and equivalent fixed tool cutting processes are compared in terms of cutting tool temperatures generated.