pH sensitivity of protein mediated gold nanocrystals modified SiO2 have been investigated using a capacitive EIS (electrolyte-insulator-semiconductor) structure and compared with bare SiO2. The SiO2 surface was first silanized using phenyltriethoxy and then a chaperonin protein array was formed on SiO2 surface. Finally, the chaperonin protein lattice is used to deposit gold nanocrystal on SiO2 surface in the EIS structure. The electrochemical characterization of EIS sensors was done by means of C-V measurement in pH buffer solutions of values from 2 to 12. The average sensitivity of gold modified SiO2 senor was 33 mV/pH and SiO2 senor was 35 mV/pH while the linearity was 99.37% and 98.35%, respectively.