In order to measure thermal interface resistance (TIR) at temperatures up to 700 °C, a test apparatus based on two copper 1D reference bars has been developed. Design details are presented with an emphasis on how the system minimizes the adverse effects of heat losses by convection and radiation on measurement accuracy. Profilometer measurements of the contacting surface are presented to characterize surface roughness and flatness. A Monte Carlo method is applied to quantify experimental uncertainties, resulting in a standard deviation of thermal resistance as low as 2.5 mm2 K/W at 700 °C. In addition, cyclic measurements of a standard thermal interface material (TIM) sample (graphite foil) are presented up to an interface temperature of 400 °C. The interface resistance results range between approximately 40 and 100 mm2 K/W. Further, a bare Cu–Cu interface is evaluated at several interface temperatures up to 700 °C.