Fuel cells operating at elevated temperatures are suitable for medium and large scale applications, thus they have good prospects for commercialization. Molten Carbonate Fuel Cells (MCFCs) appear among the most promising in this respect. MCFC has a number of advantages over other high temperature fuel cells: (i) high energy efficiency and high electromotive force, (ii) nickel instead of platinium as a catalyst, (iii) electrolyte thickness of about 1 mm is much more easier to manufacture, (iv) it can be used as a CO2 separator due to its ability to capture carbon dioxide from the cathode side. LiAlO2 is a very effective support for molten carbonates, but it is very expensive as there are few manufacturers. In a single conducting electrolyte, the cathode inlet needs to contain an adequate ratio of CO2 to O-2, (2:1), this results in low oxygen partial pressure at the cathode inlet (taking into account that oxygen is being delivered in air at an initial molar fraction of 21%). The low pressure of oxygen results in a relatively low Nernst voltage and feeds through into lower MCFC performance. By using a dual conducting electrolyte, a more favorable ratio between carbon dioxide and oxygen (CO2:O-2<2) can be obtained, achieving higher maximum voltages which in turn translate into higher efficiency. Excellent performance was obtained for the Sm-0.2 center dot Ce-0.8 center dot O-1.9-carbonate composite and nanocomposite electrolytes prepared using eutectic carbonates with a mixture of Li-2 center dot CO3/Na-2 center dot CO3. High temperature membranes based on dual carbonate and oxide electrolytes have been shown to selectively separate CO2 above 600 degrees C. In this paper, the testing results of a composite electrolyte layer based on Samaria Doper Ceria and Lithium/Potassium carbonates for its electrochemical performance as a matrix for MCFC are presented. The voltage current density curves were collected in a range of temperatures: 500-800 degrees C. The idea is to use a dual conductive composite electrolyte as a matrix for Molten Carbonate Fuel Cells. This results in an improvement in the performance of the MCFC, by, in particular, increasing ionic conductivity through additional O-= conduction. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.