Because of the superior material properties of diamond, high performance in high-temperature power device application is demonstrated in both the computational and the experimental studies. A calculated Baliga limit of diamond Schottky barrier diode (SBD) based on 1D model indicates that an increase in on-resistance is highly expected within the high blocking voltage region and will be remarkable at high temperature conditions. Because of the high barrier height of diamond SBDs, the reverse leakage current is suppressed even at high temperatures. From the high-temperature stability test, stable interfaces of metal/diamond contact with constant Schottky barrier height have been confirmed. The SBD works for more than 1500 hrs at 400oC.