Porous silicon quantum dot (PSi-QD) was prepared from p-type silicon (100) using the electrochemical etching technique. The prepared PSi-QD was then applied as an extended gate field effect transistor (EGFET) in the synthesis of a PSi-QD based pH sensor. The morphology, structural properties, and pores of the prepared PSi-QD layer were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The average pore size of the PSi-QD was 5.8 nm with an average pore depth of 3.43 μm. The sensitivity, linearity, and hysteresis measurements of the sensor were determined for different pH buffer solutions. The sensor displayed a voltage sensitivity of 108.3 mV/pH with linearity of 98.97% for the linear regime, while the current sensitivity for the saturated regime was 2.65 μA1/2/pH with linearity of 99.81%. The net hysteresis value of the sensor was approximately 14 mV. The repeatability deviation at pH7 was 0.86%. The stability and reliability of the sensor in terms of coefficient of variation (C.V.) were 0.76%, 0.93%, and 0.98% for pH4, pH7, and pH10, respectively. Based on its high sensitivity, good linearity and low hysteresis as well as its good repeatability, stability and reliability, the PSi-QD EGFET based pH sensor is considered a viable device for the detection of hydrogen ions.