We report here the fabrication of clean dendritic gold (DG) directly on a smooth Au electrode via square wave potential pulses (SWPPs) in a blank H2SO4 solution containing no Au(III) species and additives. The effects of potential range, frequency and duration time of SWPPs and H2SO4 concentration on the construction of DG were systematically investigated. A possible mechanism was proposed to explain the growth of DG. The whole process was templateless and surfactantless, and therefore effectively avoided possible contaminations that occurred in other synthetic routes. Further, the prepared DG electrode functioned as a scaffold to support electrodeposited Pt clusters, producing Pt-decorated DG (Pt-DG) electrodes. The electrocatalytic properties of Pt-DG electrodes with various Pt loadings were examined for the oxidation of formic acid. The low Pt loading Pt-DG demonstrated different electrochemical behavior from that on Pt-decorated smooth gold (Pt-SG) and on Pt-decorated gold nanoparticles because there were more defect sites like steps and edges on the DG surface. Ensemble effect, as well as electronic effect, accounts for the improved electrocatalytic activity of low Pt loading Pt-DG. (C) 2012 Elsevier Ltd. All rights reserved.