The invention concerns an apparatus for the plasma treatment of substrates in a plasma discharge excited by a high frequency between two electrodes 3, 8 to which power is supplied by a high frequency source, where the first electrode is configured as a hollow electrode 3 and the second one as an electrode 8 holding a substrate 7 and situated upstream of the hollow chamber 10 of the first electrode which it also passes. The hollow electrode is enclosed by a dark space shield and has an edge pointing in direction of the second electrode and also has projection located between the edge. These projections are on the same potential as the second electrode. The radio frequency power is thus decoupled from the substrate bias voltage (selfbias) and the distance between the first and the second electrode can be changed.