On the basis of a linear complementarity, a mathematical formulation of thermomechanical frictional contact is presented. Depending on the status of contact, either a conduction condition or an insulation condition is applied. A complementarity condition between heal flow and temperature difference along the contact surface is found assuming that no thermal contact resistance exists. This thermal complementarity condition is implicitly related with the mechanical one. The resulting linear complementarity with additional constraints is solved by a modified Lemke's algorithm. Two numerical examples are presented to illustrate the procedure and solution behaviors.