In this study, we utilize the commercial device, Sentron 1090 Al2O3 gate pH-ISFET to study the sensitivity and hysteresis behavior. The experimental results show that the Al2O3 materials have a fairly high response, and the sensitivity was obtained from the pH response of Sentron 1090. The hysteresis effect in a Sentron 1090 Al2O3 gate pH-ISFET was studied by exposing the device to two cycles of pH values. The hysteresis curves were measured in the sequence pH 8-3-8-11-8 and pH 7-3-7-11-7 at different loop time. According to experimental results, the hysteresis width is increasing with loop time and measuring path. We also observed and compared the pH sensitivity and magnitude of the hysteresis width with others pH-sensing gate ISFETs studied in our laboratory and the related literature.