Capacitance-voltage (C-V) characteristics of Ni-SiO2-SiC (n-type, Si face, and C face) metal-oxide-semiconductor structures have been studied at temperatures of 25, 100, 200, 300 and 350 degrees C. Wet oxidation was used to grow a layer of SiO2 of 440 and 800 Angstrom thickness on the Si- and C-face of 6H-SiC, respectively. The characteristics of SiC MOS capacitor at 350 degrees C for Si-face and at 200 degrees C and above for the C-face, resemble silicon MOS structure at room temperature. An analysis of C-V curves shows that as the measurements temperature increases the curves shift toward the right for the Si-face and toward the left for the C face. Repeated measurements of sample show that C-V curves measured at 350 degrees C remain the same in both the C and Si face, whereas C-V curves at room temperature shift toward right, especially after first cycle of high-temperature measurements on the Si face. No apparent shift is visible at room temperature for the C face.