Nanocomposite layers have been obtained by electrochemical deposition of silicon carbide nanoparticles (mean diameter 20 nm) in a nickel plating bath. The influence of nanoparticles on nickel electroplating is studied by electrochemical impedance spectroscopy (EIS) at cathodic potential. Cathodic polarization diagrams have been determined in the electrolyte with and without nanoparticles. We show that incorporation of 20 nm SiC particles into nickel deposition modifies the impedance and cathodic polarization diagrams in correlation with the modification of the surface morphology and crystallinity of nickel matrix.