In applications involving substantial friction, surface failure is an inevitable phenomenon. Friction induced failure typically involves the generation of considerable heat. Existence of significant frictional force leads to relatively high interface temperature as a result of dynamic nature of flash temperatures at the contact areas. A first step in predicting friction induced failure is to develop an accurate thermomechanical model of the friction system. A thermomechanical model is developed in this paper based on a lumped parameter representation of a two-disk brake. A disk is viewed as consisting of three main regions: (1) the surface contact, (2) the friction interface, and (3) the bulk. The lumped parameter model is obtained by dividing a disk into a number of concentric rings and stacked layers. The friction layer contains both the interface and contact elements, each includes the equivalent thermal capacitance and conductive resistance. The contact capacitance and resistance are described in terms of the elastic contact interaction between the surfaces of the two disks. Therefore, they are obtained using the Greenwood and Williamson model for contact of rough surfaces. Each is described as a statistical summation of the micron-scale interaction of the surfaces.