The electrochemical behaviour of a platinum(II) anti-tumour drug (cis-platin) has been investigated at the platinised platinum and carbon paste electrodes using cyclic voltammetry. Measurements performed in neutral aqueous media at the platinised platinum electrode as a function of free chloride ions have enabled the nature of oxidised species to be established and the sensitive determination of the molecule within the range of concentration 1 x 10(-3) - 1 x 10(-5) M to be realised. Use of the carbon paste electrode offers interesting insights into the redox stability of the molecule and allows the hydrolytic degradation of cis-platin to be followed as a function of time.