Abstract The crystal characteristics of gold particles grown on an amorphous carbon film in a 10 −3–10 −5 M HAuCl 4 solution at different electrode potentials have been studied by means of electron microscopy and electron diffraction. The results show that the gold particles grown at different electrode potentials have different shapes, i.e., the particles formed at negative potential (versus SCE) consist mainly of icosahedral and decahedral particles, while at positive potential (versus SCE) fcc octahedral single crystal particles are dominant. Decahedral particles grown to 80 nm and icosahedral particles grown to 32 nm were observed at negative potentials. At positive potentials the icosahedral and decahedral particles only grew to about 10 nm. From these results it is clear that at negative potentials the gold particles prefer the growth of decahedral and icosahedral structures, but at positive potentials the fcc crystal structure is preferred. The characteristics of the gold particles depend upon the electrode potential at which the particles are grown, but it is not influenced by the concentration of the HAuCl 4 electrolyte. The results will be discussed in relation to the potential-dependent surface reconstruction of Au(111), Au(110) and Au(100) surfaces.