The present work reports on the influence of nickel molar loading and impregnation solutions, nitrate salts and copper and nickel ammonium complexes, on the synthesis of Ni-Cu catalyst supported on alumina for obtaining carbon nanofibers by catalytic chemical vapor deposition of methane. These catalysts were characterized by N2 adsorption-desorption, x-ray Diffraction, Thermo-Gravimetric Analysis and Scanning Electron Microscopy for the carbon nanostructures analysis. The catalytic activity was studied through the carbon deposition under different conditions of temperature (600 °C and 650 °C) and pressure (in ultra-low pressure conditions and 0.5 bar). As a main result, catalyst using nitrate salts impregnation leads to the major carbon nanofibers yielding at the temperature of 600 °C. On the other hand, catalysts synthesized by ammonium complexes impregnation present also improved characteristics compared to conventional catalysts that allows considering this methodology as an interesting alternative in carbon nanofibers producing. © 2018 IOP Publishing Ltd.