Aiming at a better knowledge of the kinetics of the Ni-P electroless processes we have carried out a steady-state polarization investigation and electrochemical impedance measurements, not only at the deposition potential but also in the cathodic and anodic ranges. We studied the effect of solution pH, nickel sulfate and hypophosphite concentrations. A reaction path is developed, which accounts for the main features observed. It also explains the interqactions between the anodic and cathodic processes;