This paper analyses the deposition of the mercuric complexes from dilute solutions of HgCln(2-n) and high concentrations of NaCl, taking into account the reduction of O-2 as a simultaneous electrochemical reaction. Studies with a vitreous carbon rotating disk electrode were performed to determine the potential regions where the reactions take place and also to calculate the kinetic parameters under experimental conditions. Reproducible results were obtained only when a mercury film was deposited on the vitreous carbon surface prior to each experiment. Potentiodynamic polarizations were obtained from 5 x 10(-4) M Hg(II) solutions and different NaCl concentrations ranging from 1 M to 4 M, in the presence and absence of dissolved oxygen. The mercuric complex deposition and the oxygen reduction proceeded via mixed control within the first 50 mV overpotential, followed by a diffusion control. After -0.450 V vs see the H-2 evolution started. This reaction occurred at free vitreous carbon left between the liquid mercury droplets where the hydrogen overpotential is smaller. Kinetic parameters as well as the reaction rate expression for mercury deposition from its chloride complexes were obtained.