This paper reports the high temperature test results of SiC p–n junction diode up to 873K. No significant change in diode series resistance (Rs) and a diode ideality factor of 1.02 were confirmed in air. We used the 4H-SiC diode which had a contact pad area of 300μm×300μm and a junction area of 220μm×220μm. Ohmic contact on both p and n (i.e. front and back) sides were made by Ni, because nickel silicide (NiSi) provides good ohmic contact for high temperature applications. The electrical contact pads of the SiC diode were made by sputter-depositing Ni or Pt on the NiSi ohmic contact. High temperature aging tests at 673K, 773K and 873K were carried out in air, and the forward current–voltage (I–V) characteristics of the SiC diodes were measured at different time intervals to observe change in the junction and series resistance. Stable p–n junction characteristic and constant series resistance were confirmed for the Pt-metalized diodes at 673K, 773K and 873K. However, the Ni-metallized diodes showed marginal increase in series resistance due to the oxidation of Ni metal contacts.