The lateral resistance of a thin metal film (<30 nm) depends on the presence or absence of other species at its surface. This phenomenon is investigated in terms of analytical applications for the determination of heavy metals in aqueous solutions. Therefore, microstructured polycrystalline noble metal electrodes have been fabricated by means of thin-film techniques; their resistance-potential behaviour has been recorded during the electrochemical deposition and dissolution of various heavy metals such as Cd, Pb, Ni, Tl and Zn. During the deposition of the heavy metals, an increase of the electrode’s lateral resistance has been observed, whereas the subsequent dissolution of the deposited heavy metals decreases the resistance to its initial value. The magnitude of the resulting resistance change linearly depends on the heavy metal content of the solution (from ppb (μg/1) to ppm (mg/1)). The resistance measurements show a specific selectivity in the electrode potentials of thermodynamic equilibrium between the deposited (i.e. reduced) and the dissolved (i.e. oxidised) form of the species. Corresponding to voltammetric methods, this new principle is called voltohmmetry.