Abstract: An apparatus for plasma treatment of plate-shaped substrates comprises a reaction vessel (2) provided with supply opening (48) and discharge opening (50) for a reaction gas. Anode (46) and a plurality of cathodes (13) are also provided. At the periphery of the cathodes (13) are provided gas flow passges (40, 41) through which the reaction gas may flow from the gas supply opening (48). The gas flow passages (40, 41) are provided on the side of surfaces (15c, 16c) of the cathodes receiving small plates. Discharge opening (50) is arranged downstream of gas flow passages (40, 41). The apparatus may also comprise a removable tray (38) to load and unload the small plates, and the flow passages (40, 41) may be delimited by the walls of the electrodes and of passages traversing the tray (38).