In this paper, three composite electrolytes (Ce0.8Sm0.2O1.9/Na2CO3) SDC, (Ce0.8Gd0.2O1.9/ Na2CO3) GDC and (La0.8Sr0.2Ga0.8Mg0.2O3-delta/Na2CO3) LSGM have been studied to review the effect of Na2CO3, present as second phase, and effect of Ni support, sintering and pressure for dry pressing for fuel cell performance. The electrolytes were prepared through a co-precipitation method. Different techniques were used to characterize the prepared electrolytes. The crystal structures were determined using x-ray diffraction (XRD) and structural morphologies were analyzed through scanning electron microscopy (SEM). The four probe dc conductivity and two probe AC impedance analysis were carried out in open air. The fuel cell performance was determined with and without Ni support on anode side which resulted in a considerable difference in obtained peak power densities. It is suggested that prepared electrolytes can find potential applications in low temperatures Solid Oxide Fuel Cells (LT-SOFCs). (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.