Nickel thin films were deposited with Ni(C5H5)2 \NiCp2, bis(cyclopentadienyl)nickel, nickelocene]/H2 at various temperatures and H2/Ar ratios. The deposition rate, resistivity, purity, crystal structure, and surface morphology of the nickel film were investigated. Also, thermal analysis was done to find out the dissociation characteristics of NiCp2, and Fourier transform infrared spectroscopy diagnostics were carried out to study the gas phase reaction kinetics of NiCp2. Nickel films deposited at higher temperatures (>225 °C) had high carbon content and high resistivity. At higher temperatures, thermal decomposition of NiCp2 and subsequent decomposition of Cp induced a large amount of carbon incorporation into the film. At lower temperatures (<190 °C), the slow dissociation of NiCp led to some extent of carbon incorporation in the film. Nickel films deposited at around 200 °C showed carbon content lower than 5% and lower resistivity because of the effective dissociation of Ni–Cp and desorption of Cp from the surface. Nickel films deposited with hydrogen addition showed higher purity, crystallinity, and lower resistivity due to the removal of the carbon on the surface.