Porous combustors have been studied intensively concerning the combustion of natural gas. The advantages of combustion in porous inert media, such as low emissions, high power turndown ratio of typically 10:1 and compactness, can also be used for different chemical gas phase reactions, e.g. the HCl synthesis from H-2 and Cl-2. The advantages of porous reactors result from the heat transport properties of the porous medium, i.e. emissivity and conductivity. Heat transport mechanisms and chemical reactions were implemented in a numerical code in order to investigate the H-2/Cl-2 system. Important parameters of the reaction, e.g. the laminar flame speed and the adiabatic flame temperature, are higher for the H-2/O-2 reaction compared to the CH4/air combustion. By studying the influence of H2O and HCl as inert components it was shown by numerical investigations that the maximum temperature could be decreased to a level, which makes the usage of a porous reactor feasible. A porous reactor for laboratory use was tested with O-2/CH4/N-2 combustion, which delivers even higher adiabatic temperatures and flame speeds than the H-2/Cl-2 reaction. Finally, experiments with H-2/Cl-2/HCl reaction were carried out and first results are presented.