A device for treating a surface with a dielectric barrier plasma, wherein the surface functions as a return electrode, having a housing (1), in which a high-voltage feed line, an electrode (8) which is connected to the high-voltage feed line, and a dielectric (9), which screens the electrode (8) with respect to the surface, are located, permits the plasma treatment of highly curved surfaces and of relatively large surface areas by virtue of the fact that the electrode (8) has the shape of a circle which is mounted in the housing (1) so as to be rotatable at least to a limited degree, and projects with a spherical section from an end-side opening (5) in the housing (1), and in that the electrode (8) is coated with the dielectric (9) in such a way that its spherical section projecting out of the housing (1) is covered by the dielectric (9) in every possible rotational position.