The investigation of the Boudouard reaction and methane cracking was performed over Ni/CaO, Ni/Al2O3, and Ni/MgO. The catalysts were synthesized using co-precipitation. Both catalysts and carbon deposits were studied using AAS, BET, TPD, TPR, TPO, TOC, and XRD. The optimal temperatures for the graphite-like carbon species formation during the reactions were found to be 450 and 700 °C, respectively. The results showed that the activity of the catalytic systems is related to the number of weakly interacted Ni particles with the support. This research provides insight into the carbon deposit formation mechanism and the support role in the reactions.