The ability of spontaneously adsorbed monolayers possessing terminal sulfonate groups to prevent electrode surface fouling by surfactant-containing solutions was examined. Films of 3-mercaptopropane sulfonate (MPS) on polycrystalline gold electrodes were prepared from acidic solution and characterised by reductive desorption. The voltammetric reduction of lead(II) ions at such electrodes revealed an enhanced current for underpotential deposition (upd) compared to the current observed at a clean polycrystalline gold electrode. The enhanced upd current was maintained in the presence of bovine serum albumin (BSA), indicating the ability of the MPS film to prevent adsorption of BSA on the gold electrode and the consequent fouling of the surface. Using the enhanced upd current, 1 µM Pb²⁺ could be detected in solution using square wave voltammetry. This work has implications for analytical applications of monolayer-coated electrodes.