A scanning electrochemical microscope (SECM) has been applied to the local deposition of Co microstructures on Au. The method employs a Co microelectrode to generate a potential-controlled flux of the respective ions in an aqueous solution. The microelectrode was positioned at a precisely defined distance above a gold surface using the steady-state current for oxygen reduction. The optimum conditions for Co dissolution and deposition were identified from voltammetry and chronoamperometry. Applying these conditions in the SECM configuration facilitated the successful deposition of Co structures. The dissolution and uptake of Co on the Au surface was investigated using SECM double potential step chronoamperometry. (C) 2004 The Electrochemical Society.