The first a-Si:H MOSFET having native oxide at the insulator/a-Si:H interface is reported. Anodic oxidation in the AGW electrolyte is applied to Al/a-Si:H structures to form Al2O3/native oxide/a-Si:H gate structures. Resulting FETs show typical effective mobilities of 0.02 cm2/V s after proper low-temperature annealing in H2. Anodic oxidation is thus proved to be applicable to a-Si:H device technology as a low-temperature oxidation process.