The growth of copper dendrites was investigated in oxalic acid media on microelectrodes of disk and square geometry and of sizes ranging from 0.3 to 10 mu m. The microelectrodes were implanted by pairs on a special microcircuit built with the techniques of the microelectronic industry. Disk-disk and square-bar pattern behaviors were examined by recording the current transients occurring when a potential difference was applied between the two microelectrodes of a pair, and dendrites grew on the cathode whereas the anode dissolved. After some time the dendrites growing on the cathode reached the anode and provoked a short circuit. Then, at the end of the growth, the dendrites were observed by means of a scanning electron microscope. The influence of the applied potential difference, the concentration of oxalic acid, and the distance of separation between the microelectrodes were studied. It was shown that the growth rate of the dendrites was limited by the diffusion of the copper ions coming from the anode. Depending on the experimental conditions, filamentary or compact morphology of the dendrites were observed, depending on the magnitude of the electric field. (c) 2007 The Electrochemical Society.