Abstract: The present invention relates to an apparatus for treatment of the surface of metals and metalloids, metal oxides and metalloid oxides, and metal nitrides and metalloid nitrides using the action of electric plasma. The invention disclosed herein includes at least one electrode system (1) consisting of electrode systems (2) and (3) situated inside of a dielectric body (4). The electrode systems (2) and (3), above which diffuse plasma is generated preferably at atmospheric pressure, are situated on the same side of the treated surface (5) and are energised by alternating or pulsed electrical voltage applied between them. The invention further relates to a method for treatment of the surface of metals and metalloids, metal oxides and metalloid oxides, and metal nitrides and metalloid nitrides using the action of electric plasma, consisting in treating such surfaces with diffuse plasma generated using the apparatus according to the invention, preferably at atmospheric pressure.