Mo-promoted alumina supported Ni catalysts were prepared through a conventional impregnation method and tested in dry reforming of methane (DRM) at temperatures from 550 to 850 degrees C. The catalysts were characterized by means of H-2-temperature programmed reduction (H-2-TPR), CO2-temperature programmed desorption (CO2-TPD), X-ray diffraction (XRD), N-2 physisorption and Raman spectroscopy. Mo-promotion caused a reduction in the DRM catalytic activity. The weaker interaction between NiO species and the alumina support, the formation of a MoNi4 phase, and the lower basicity of this Ni-Mo/Al2O3 catalyst were identified as the main causes for its lower activity. However, pre-reducing the Ni-Mo/Al2O3 catalyst at temperatures lower than 700 degrees C, instead of 900 degrees C, resulted in a considerable increase of its catalytic activity. This was mainly due to the formation of a separate Ni-0 phase that did not interact with Mo and to an increase in medium strength basicity. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.