The Gd2O3/SiO2-stacked oxides prepared by thermal oxidation were implemented at 1000 degrees C for 5-30 min in ambient oxygen. The transmission electron microscopy results indicated that the longer the oxidation time the thicker the oxide layer. Meanwhile the grown layer surface roughness is reduced and the hysteresis of the corresponding metal oxide semiconductor capacitor is decreased. Large shifts of flatband voltages are observed when the stacks' layer (Gd2O3/SiO2) electrolyte-insulator-semiconductor structure is immersed in the pH 2, 4, 6, 8, and 10 buffer solutions, respectively. The hydrogen ion sensitivity of this structure is found to be 53.31 mV/pH.