The preparation of a thick coating of mesoporous silica (MPS) on metal substrates by electrophoretic deposition (EPD) has been studied for application to an advanced desiccant cooling system. In this study, we investigated the EPD mechanism of MPS in acetone under a constant applied voltage for the fabrication of a thick MPS coating. We consider that the main contributors to the resistance between the deposition electrode and the counter electrode are the deposited MPS layer and the EPD bath. The current density was measured during EPD under a constant applied DC voltage. The current density decreased as the EPD progressed, and the resistance increased between the electrodes. The AC impedance between the deposition substrate and the counter electrode was measured in the range of 10 Hz-80 kHz. We observed a single semicircle in the impedance plots. We investigated the influence of the MPS powder concentration of the EPD bath and the amount of deposition layer on the total resistance. We found that the resistance caused by forming the MPS layer increased as EPD progressed whereas the resistance of EPD bath was almost constant through the EPD process. Moreover, we determined the EPD mechanism of MPS powder in acetone.