A cobalt-boron/nickel-boron (Co-B/Ni-B) nanocomposite was synthesized in a two-step process by in situ reduction of nickel and cobalt salts. Characterization of the nanocomposite using X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett--Teller adsorption analysis showed that the Co-B nanoparticles were well dispersed on the Ni-B surface. Enlisted as a catalyst in the hydrolysis of ammonia borane (AB) for hydrogen generation (HG), the nanocomposite exhibited better catalytic activity than Co-B and Ni-B at room temperature; the HG rate was 1368.2 mL min(-1) g(-1) at 25 degrees C in a 1.5 wt.% AB solution, with a low activation energy of 33.5 kJ mol(-1). The effect of the complexing agent (sodium citrate) on the nanocomposite's catalytic activity was also investigated. In addition, recycling tests showed that Co-B/Ni-B was still highly active and preserved 84% of its initial catalytic activity after 11 recover-and-reuse cycles. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.