The adsorption behaviour of benzenesulphonate (BS) and p-toluenesulphonate (PTS) anions at an Au(210) single-crystal electrode was investigated employing cyclic voltammetry and capacity measurements at constant ionic strength. It was found that the charge sigma(i) due to specifically adsorbed anions is significantly greater (in the region of saturation) for the BS anion than for the PTS anion. It was postulated that BS anions can assume two different orientations at the electrode surface. A more detailed study of the adsorption process based on the Frumkin isotherm was performed for PTS anions. The inner-layer capacity was analysed into its components. The analysis indicated that the molecular structure of a given anion determines its behaviour during the adsorption process.