The electrical characteristics of AuGe/SiO2/p-Si (MOS) capacitor were analyzed by impedance spectroscopy in a wide frequency range. The equivalent circuit model consisting of a parallel resistor (R-p) and capacitor (C-p) in series with a series resistance (R-s) was found to give a well fit to the measured data of MOS capacitor. The values of R-s, R-p and C-p were obtained from the Cole-Cole plots indicating a single semicircle. The value of C-p remains almost constant while the R-p decreases with bias voltage. Also, the variation of resistance with dc bias voltage showed that conduction mechanism of the capacitor was space charge limited current with exponential trap distribution.