A previously developed mesoporous Ni-CaO-ZrO2 catalyst (NCZ) was submitted to dry reforming of methane (DRM), and the influence of feeding compositions on the properties of accumulated carbon was comprehensively studied. To this end, the used catalysts (NCZ-x) were characterized with a particular focus on the carbon residuals, using X-ray diffraction, N-2 adsorption, transmission electron microscope, scanning electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy, etc. The results indicate that by varying the composition of the feeding gas, the morphology and chemical inertness of the accumulated carbon changed considerably, and the deactivation of the NCZ catalyst under CH4-rich conditions can be associated with the formation of coating carbon species that leads to the coverage of highly active Ni nano particles (NPs). (C) 2014 Elsevier Ltd. All rights reserved.