Low-pressure, glow discharge plasma catalytic CO2 methanation was investigated in the presence of Ni/Al2O3, Ni/SiO2 and Ni/CeO2-ZrO2 catalyst. The prepared samples were characterized by ICP, XRD, low-temperature N2 sorption, H2-TPR, dielectric constant measurement and FT-IR in-situ adsorption of NO, CO and CO2. The performed characterization allowed selecting the optimal conditions of catalyst preparation as well as explaining the results of plasma-catalytic tests. The application of various supports had a significant effect on plasma properties and thus dissociation of CO2 in the gas phase. It affected plasma stability as well, which decreased with the increasing values of the dielectric constant. Ni/Al2O3 sample showed the best performance in terms of CH4 production. The positive effect on the catalytic activity in thermal CO2 methanation was observed for Ni/Al2O3 and Ni/SiO2 samples. Adsorption of probe molecules (NO, CO and CO2) performed for fresh reduced and spent catalysts allowed to get insights into plasma-catalytic reaction mechanism and to explain the effect of plasma promotion on the performance of the catalysts in thermal CO2 methanation.