The dielectric permittivities of fee yttria-stabilized zirconia (YSZ) and ceria (CeO2) thin films as-grown on n-doped Si(100) substrates by electron beam evaporation at 200 degrees C in the metal-insulator-semiconductor (MIS) configuration have been investigated. Two independent methods were used for this purpose, the high frequency limiting capacitance C-p and feedback charge C-V plots. The values obtained are 16.8 (YSZ) and 2.8 (CeO2) in the case of C-p and 18.3 (YSZ) and 3.4 (CeO2) from the C-V measurements. The hysteresis of C-V curves observed for both Al/YSZ and CeO2/Si/Au structures can be ascribed to the slow redistribution of negative mobile charges (oxygen ions O2-) present inside the YSZ and CeO2 films.