A preliminary investigation of the electrochemical deposition of Pt, Pb, and Hg adlayers on conductive diamond thin‐film surfaces has been made using cyclic voltammetry and scanning electron microscopy. The diamond thin films employed were polycrystalline, grown on conductive Si substrates (1 cm2) to a thickness of ca. 14 μm, and doped with boron at a nominal atomic concentration ranging between 1019 and 1020 cm−3. The cyclic volammetric measurements were performed both in a conventional glass electrochemical cell and in a thin‐layer flow cell. The results demonstrate that metallization of diamond film surfaces electrochemically is feasible, opening the door for the development of novel catalytic electrodes, sensors, and detectors using this advanced material.