A new method for preparing platinum-modified electrodes by attracting nanometer-sized platinum particles from hydrosol to -SH coated surface of conductive glass obtained through Langmuir technique has been proposed. The electrode possessed a surface modified with homogeneously distributed platinum nanoclusters and a low platinum loading. The catalytic activity of thus fabricated electrode for the triiodide reduction was investigated by electrochemical impedance measurements. The charge-transfer resistance at the interface of electrolyte/electrode was much lower and the corresponding exchange current density was several hundreds micro ampere per centimeter square larger than conventional thermal decomposed Pt-modified electrode and Pt foil electrode. (c) 2005 Elsevier B.V. All rights reserved.