An electrochemical characterization (by linear sweep cyclic voltammetry and chronoamperometry at constant potential) of a cast Co-Cr alloy and of pure chromium was performed and their behaviour compared using NaCI 0.15 M and albumin-containing solutions as electrolytes. The amount of ions released was determined. The protein detrimental effect over both materials was detected. Metallic surfaces were also investigated by X-ray photoelectron spectroscopy and observed by means of optical and scanning electron microscopy.