In the present work, the microstructures of YSZ electrolyte films, which were sintered at various temperatures in the range of 1300-1600 degrees C, were investigated. First, a suitable and uniform film was deposited on the surface of NiO-YSZ composite by EPD. After the consequence sintering, the surfaces of deposited YSZ films were observed by SEM. In addition, other characteristics of the YSZ electrolyte films such as surface roughness and morphology of the sintered films were investigated by AFM. The ability of ionic transfer and permeability of the YSZ electrolyte was examined by electrochemical impedance spectroscopy at different temperatures. It seems that the YSZ electrolyte sintered at 1400 C was appropriate for SOFCs applications, because this film had the minimum impedance, minimum roughness and the maximum conductivity. Furthermore, the temperature of 1400 degrees C was the minimum temperature in which a dense film of YSZ was formed uniformly on the surface of anode and coated it completely. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.