This work demonstrates the electrochemical synthesis of nanoscale gold particles using a surfactant solution. Tetradodecylammonium bromide (TTAB) surfactant was applied to stabilize the gold clusters. Experimental results reveal that the size of the produced gold nanoparticles is controlled by the amount of TTAB surfactant, the current density, and the growth temperature. The size of the gold nanoparticles can be controlled in the range 58.3-8.3 nm. The particle size decreases as the amount of TTAB increases from 1 to 90 mg. The optimal current density in this study was 3 mA/cm(2). The size of the produced nanoparticles increases linearly with the growth temperature from 25 to 60 degrees C. The gold nanoparticles were observed by transmission electron microscopy, ultraviolet-visible spectrometry, and X-ray photoelectron spectroscopy. A mechanism for electrochemically controlling the size of the gold nanoparticles is presented. (c) 2006 The Electrochemical Society.