This work reports the synthesis of a new matrix material (graphene-supported NiCl2 and CoCl2 nanoparticles) for loading ammonia borane (AB) and investigates their catalysis effect for dehydrogenation properties. The NiCl2 and CoCl2 nanoparticles are obtained with the size around 3-10 nm and dispersed uniformly on the surface of graphene, which exhibit enhanced catalysis effect for the dehydrogenation of AB. The AB@NiCl2/CoCl2-graphene system, obtained via loading AB on the NiCl2/CoCl2-graphene scaffold, shows much lower onset dehydrogenation temperature of 60-90 degrees C and effective suppression of those byproducts such as ammonia, diborane and borazine formations compared with pristine AB. Meanwhile, the activation energy of AB@NiCl2/CoCl2-graphene has been calculated to explore the improvement of dehydrogenation kinetics of AB under the existence of graphene-supported NiCl2 or CoCl2 nanoparticles. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.