In the present work, the design and testing of a very compact reaction system thermally integrated for the distributed hydrogen production by natural gas reforming is reported. The system is based on hydrocarbon Auto-Thermal Reforming, followed by a Water-Gas Shift module. A compact heat exchanger was placed between the two catalytic stages, in order to assure an appropriate thermal integration, thus avoiding any other external heat duties. Experimental results demonstrated that the integrated configuration assured a good management of thermal fluxes in the system, in which an effective heat recovery from ATR exhaust gas to reactants was realized. Preliminary tests showed very impressive performances of the system, both by processing methane and natural gas. Despite a quite inefficient WGS stage, the processor was able to produce up to 10 Nm(3)/h of hydrogen, assuring a thermal efficiency higher than traditional systems. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.