In this study, Nickel nanoparticles/reduced graphene oxide was successfully prepared through an in-situ hydrothermal process by applying graphene oxide as a precursor that was applied as a catalyst for converting CO2 into CH4. NiNPs/rGO were characterized using UV-Vis spectrophotometer, Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Energy-Dispersive X-Ray Spectroscopy (EDS). The characterization of the UV-Vis spectrophotometer shows NiNPs/rGO gave absorption at 260 nm which indicates red shifting from GO absorption peak (230 nm). FTIR spectra of NiNPs/rGO shows a decreasing in absorbance from the peaks of the oxygen-containing group (i.e. carboxylic and hydroxyl group) previously contained in the GO, moreover disappearance of the absorption peak at 1736 cm-1 (C=O) in NiNPs/rGO also indicates that reduction process from GO into rGO has been successfully carried out. The construction of Nickel nanoparticles on the surface of the rGO was proven from the results of EDX (% mass) shows the presence of C (21.84 %), O (5.58 %), and Ni (72.58 %) on the surface of NiNPs (30 %)/rGO. In its application as catalysts, the NiNPs (30 %)/rGO catalysts have shown a good activity in the process of CO2 methanation (i.e. CO2 conversion into CH4). Initial catalytic test had been done to evaluate the effect of reaction temperature on CO2 methanation using NiNPs (30 %)/rGO as catalyst. The catalytic test result shows that catalys could produce methane as the main product with highest value of 17.63 % at 673 K.