A method for patterning layers made of ruthenium or ruthenium(IV) oxide and a capacitor comprising at least one electrode which is constructed from ruthenium or ruthenium(IV) oxide at least in sections. A layer made of ruthenium or ruthenium(IV) oxide is deposited on a substrate and said layer is subsequently covered with a covering layer at least in sections. Through heat treatment of the construction thus obtained in an oxygen atmosphere, the ruthenium is converted into RuO.sub.4 in the uncovered sections and removed by sublimation. The method enables the simple patterning of layers made of ruthenium or ruthenium(IV) oxide and the construction of complex structures, such as trench capacitors, for example.