The electrochemical study on the peptidic fragment Lys-Cys-Thr-Cys-Cys-Ala [56-61] MT I (FT) in the presence of cadmium was performed by cyclic voltammetry using a hanging mercury drop electrode in order to elucidate the diffusion-adsorption processes. The influence of scan range, number of cycles, scan rate and concentration was investigated. The variation of the initial and final potentials modify the voltammetric features strongly due to changes of concentrations of species near the electrode surface. For the 1st cycle, linear relationships were found between the peak current of the different peaks and the square root of the scan rate indicating that the electrochemical mechanism is mainly diffusion-controlled. The peak current as a function of the total concentration is also linear, at least for a given range of concentration. For concentrations of the mixture FT:Cd = 1:1 higher than c similar to 30 mu M, an adsorption pre-peak was detected during the negative scan. The electrochemical systems are reversible. The evolution of voltammograms was investigated for the sequential addition of cadmium to the peptidic fragment.