Upon the application of ultrashort voltage pulses electrochemical reactions can be spatially confined with nanometer accuracy, which allows for high precision machining of electrochemical active materials. As an example, electrochemical machining parameters for the micromachining of Ni are derived from conventional electrochemical cyclic voltammetry. Depending on the average potentials of tool and workpiece, overall corrosion of the workpiece and the location of the counter reaction of workpiece dissolution can be controlled. The pulse duration provides a direct control for setting the machining accuracy. Machining precisions below 100 nm were achieved by the application of 500 ps voltage pulses. (C) 2003 Elsevier Ltd. All rights reserved.