A plasma reactor has a reactor vessel and a pair of electrodes in the form of spaced apart and oppositely disposed metallic surfaces defining therebetween a plasma discharge space. At least one of the metallic surfaces is the surface of a metallic plate having a plurality of gas feed openings extending through the metallic surface towards said discharge space and from a distribution chamber extending along the plate opposite the discharge space. The distribution chamber has a wall opposite and distant from the plate and includes a gas inlet arrangement with a plurality of gas inlet openings distributed along the wall and connected to one or more gas feed lines to the reactor. A gas flow resistant coefficient between the one or more gas feed lines and at least a predominant portion of the connected inlet openings are at least substantially equal.