In this study, the hydrogenated amorphous silicon (a-Si:H) which was fabricated by plasma-enhanced low-pressure chemical vapor deposition (PE-LPCVD) was used as a pH-sensitive surface and the drift behavior of ISFET was measured. To avoid the long-term drift, the ISFET was dipped in temperature-controlled standard buffer solution of pH 1, 3, 5, and 7 in closed dark box. According to these experiments, we can obtain that the drift rate depends on the pH value and increases with the pH increasing. Furthermore, the temperature of the buffer solution was changed and we obtained that drift rate shows an increase which can be calculated by the exponential expression.