High-k Al2O3 with metallic oxide thickness of about 3 nm on n-type GaAs substrate has been deposited by the atomic layer deposition (ALD) technique. Thus, it has been formed the Au-Ti/Al2O3/n-GaAs MIS structures. It has been seen that the MIS structure exhibits excellent capacitance-voltage (C-V) and current-voltage (I-V) properties at 300 K. The saturation current of the forward bias and reverse bias I-V characteristics was the same value. An ideality factor value of 1.10 has been obtained from the forward bias I-V characteristics. The C-Vcharacteristics of the structure have shown almost no hysteresis from +3 V to -10 V with frequency as a parameter. The reverse bias C-V curves have exhibited a behavior without frequency dispersion and almost hysteresis at each frequency from 10 kHz to 1000 kHz.