Here, we demonstrate a new method to measure step dipole moments for electrode surfaces in the presence of specifically adsorbed anion adlayers. The method is based on potential-dependent studies of the equilibrium shape and the equilibrium fluctuations of monatomic high Au islands as observed in scanning tunneling microscopy data. Furthermore we measure the angular anisotropy of the absolute step line tension for an Au(100) electrode in contact with KBr solution. A method previously introduced for surfaces in vacuum is now extended for electode surfaces in contact with electrolyte. (C) 2015 Elsevier Ltd. All rights reserved.