The conversion of CO2 into useful chemical or energy products necessarily requires a significant amount of energy. It is often not a one step process which results to having extremely high overall capital and operating costs. However, using the process of converting CO2 to carbon nanotubes, this limitation can be turned into an opportunity. The objectives of this project are to investigate the optimum parameters of highest CO2 and CH4 conversion into carbon nanotubes and to characterize the carbon nanotubes produced. The conversion of the mixture of carbon dioxide and methane into carbon nanotubes was conducted in a fixed bed catalytic reactor at high temperature and in the presence of Ni HT catalyst. On the other hand, the parameters were optimized using Response Surface Methodology (RSM) by manipulating the temperature, flowrate, type of catalyst in which the product was characterized using FTIR, XRD, FESEM and GC to evaluate the defects and the stability of the carbon nanotubes. The run at temperature 800°C and flowrate 500ml/min using Ni-30 HT gives the best result with the highest conversion followed by the run at 800°C and flowrate 400ml/min using Ni-30 HT catalyst. On the other hand, the run at temperature 700°C and 300ml/min using the same catalyst gives the lowest conversion of CO2 - CH4. It is proven by GC analysis that most of the carbon dioxide was converted to produce CNTs as the oxygen released were solely from carbon dioxide. XRD confirmed the presence of carbon nanotubes as the new peak corresponding to carbon in carbon nanotubes were detected. As for FTIR analysis, a signal at 1638 cm-1 attributed to the C-C stretch band of the CNTs were found. RSM verified that the input parameters reaction temperature and flowrate significantly influence CO2-CH4 conversion. © 2024 Author(s).