The advance of efficient hydrogen-air combustion systems has increasingly become of interest in the framework of the development of fuel cell systems, especially for the automotive sector. Therefore, compact modulating systems are required, with the additional demand of low emissions, to be integrated in a fuel cell system. A modulating combustion system based on combustion within inert porous media and an integrated heat exchanger has been developed and investigated. The system is able to handle premixed combustion of lean H-2/air mixtures at a surface load range of 1075 kW/m(2)-2150 kW/m(2), and a global equivalence ratio of phi = 0.5. The special hydrogen-air mixing concept eliminates the risk of flame flashback and enables operation with very low NO emissions. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.