Plasma-assisted reduction of a NiO/Al2O3 catalyst has been carried out in a H-2/Ar dielectric barrier discharge at atmospheric pressure and low temperature (<300 degrees C). The time evolution of H-2 consumption, the gaseous products, as well as the discharge power and temperature during the plasma reduction of NiO/Al2O3 have been investigated to get a better understanding of the reduction mechanisms involved in the plasma process. The effect of the Ni conductive metal sites on the physical characteristics of the H-2/Ar discharge has also been examined. The results show that the discharge power linearly increases during the plasma-reduction process, accompanied by an increase in transferred charge from 88 nC to 119 nC due to the formation of more conductive metallic Ni in the discharge gap. It is also found that plasma reduction does not change the size of Ni particles. (C) 2013 Elsevier B.V. All rights reserved.