Adsorption of benzoic acid on a polycrystalline Au electrode, obtained by electroplating of gold, has been studied in 0.1 M HClO4 using cyclic voltammetry and radiotracer technique. Adsorption has been found to take place in the entire range of studied potentials, from 0.05 to 1.75 V (rhe), with the surface concentration of the adsorbate exceeding 5 x 10(14) molecules cm-2 at saturation. Desorption into a clean supporting electrolyte is small and extremely slow. On the other hand, surface/bulk exchange of benzoic acid is much faster, attesting to the dynamic equilibrium between the adsorbed and solution species. Adsorption data and model calculations strongly indicate that two different orientations of the adsorbed molecules are present on the surface. Flat (parallel to the surface) orientation dominates at less positive potentials while the vertical (perpendicular to the surface) orientation dominates at more positive potentials. Regardless of orientation, benzoic acid adsorption on gold falls into the chemisorption category. General behavior of the system bears close resemblance to the adsorption of benzoic acid on platinum that was reported earlier in Zelenay and Sobkowski, Electrochim. Acta 29, 1715 (1984).