This work reports on the structural and mechanical properties of Ni-C films, deposited on silicon substrates by RF magnetron sputtering of a plasma-sprayed Ni-C target. X-ray diffraction was used to determine the phase structure, while the atomic composition and the chemical states were given by X-ray photoelectron and Auger electron spectroscopies. The internal stress, Young's modulus, hardness and scratch resistance were investigated, as a function of the RF electric power. The microstructure and the mechanical properties were found to be governed by the kinetic energy transferred to the growing film. In low energy conditions, the Ni-C films behaved mechanically as diamond-like carbons, and the microstructure coincided with that of an amorphous C-fcc Ni composite. Inversely, in high energy growth conditions, the films were composed of dispersed Ni3C small crystallites in an amorphous Ni-C mixture. Such a microstructure was characterized by low mechanical properties.