Wetting equilibria of organic liquids at an electrified interface-the dropping mercury electrode/aqueous electrolyte-are studied. The approach is based on measuring wetting as a function of electrical potential in aqueous dispersions by recording the double layer charge displacement current due to the attachment and spreading of organic droplets. The effects of chain length of n-alkanes, double bonds, and specific adsorption of inorganic anions on wetting have been measured. The potential range of wetting became wider with increasing chain length of n-alkanes; i.e., the critical interfacial tensions of wetting decreased in the sequence from decane to octadecane. The values of critical interfacial tension of wetting, obtained from electrocapillary curves, are in good agreement with the values calculated in the system mercury/water/n-alkane using the Young-Dupre and Good-Girifalco-Fowkes relationships. The presence of a single double bond caused a decrease in critical interfacial tension of wetting by 3.5-4 mJ/m(2), and the effect of conjugated double bonds iri squalene seems to be additive. Critical interfacial tensions of wetting are equal at the positively and the negatively charged interface for n-alkanes and for unsaturated and branched squalene as well, showing the importance of dispersion forces in hydrocarbon interaction with the mercury and water interface. However, in the presence of specifically adsorbed bromide and iodide ions at the positively charged electrode, the critical interfacial tensions of wetting increase due to the additional interfacial energy required for displacement of the adsorbed anions. The obtained results on potential controlled wetting equilibria between the mercury electrode and hydrocarbon droplets offer a rationale for electrochemical studies of dispersed systems and adhesion-based electrochemical sensors for particle analysis.