Abstract: A process and an apparatus that can be used for surface preparation and treatment of a metal workpiece surface, for example in a processing stage prior to adhesive assembly, without using environmentally harmful materials. The process comprises triggering and maintaining pulsed unipolar arc discharges between an electrode wired as an anode and a workpiece surface wired as a cathode, with the arc discharges following one another with a timing, number, and speed such that they do not cause macroscopic melting of the workpiece surface while ensuring complete extinction of the individual arc discharges. The apparatus comprises an electrode as the anode and the workpiece as the cathode, and a generator or component for generating electrical pulses.