A model is developed to explain the origin of the potential drop over the deposit during electrophoretic deposition (EPD). The magnitude of the potential drop over the deposit is explained in terms of the ion transport through the deposit, as controlled by the pore potential that is related to the thickness of the electrostatic double layer relative to the pore radius and the magnitude of the surface potential of the powder particles. This model is verified for EPD of Al2O3 powder in ethanol-based suspensions with HNO3 as a function of the operational pH.