The ion-sensitive field-effect transistors (IFSETs) with hydrogenated amorphous silicon were fabricated. In this paper, the hydrogenated amorphous silicon acting as sensing membrane was used to investigate the pH response of a-Si:H ISFET. The IDS-VG curves were carried out by I-V measuring system. The basic parameter of a-Si:H ISFET, namely sensitivity was obtained from IDS-VG curves. It exhibited a superior pH response of 50.6 mV/pH at temperature of 25 degrees C. Moreover, other characteristic parameters such as hysteresis and drift were proposed. Finally, the effects of operating temperature on sensitivity and drift were presented.