This paper presents the design and thermal analysis of a high-power Schottky diode frequency doubler at 160 GHz. The design is capable of achieving ~10% 3 dB bandwidth with a peak conversion efficiency of ~25% for an input power of 100 mW at 295 K. Thermal characterization of the design includes modelling and measurement of the power dissipation in the discrete diode under different temperatures. The results obtained from the experiments have been validated by a physics-based electro-thermal simulator for Schottky diodes.