The purpose of this study is to perform an energetic-exergetic comparison between two micro-cogenerative (CHP) units for residential applications, based on Proton Exchange Membrane fuel cell (PEMFC) and Solid Oxide Fuel Cell (SOFC) respectively. Such systems, both fed by natural gas, are dedicated to electricity and heat production for typical residential users. Simulations of two zero-dimensional models in Aspen Plus environment have been conducted in order to perform the comparison. Results obtained by the simulations have been compared on the basis of the First and the Second Law efficiencies aiming to find the most advantageous technology for small residential applications. Results analyses indicate that the PEMFC-based CHP system, operating at atmospheric pressure and low temperature, is the most efficient system. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.