Abstract: An apparatus (1) for continuous treatment of a material (M) of continuous length with a low temperature plasma of a plasma gas (G) under vacuum. The apparatus (1) includes a plasma treatment chamber (3) having a chamber wall (4) and, in the wall (4), an entrance zone (6) and an exit zone (7) for receiving and discharging the continuous material (M). Evacuating means (48) is operable to establish a vacuum in the chamber (3). Support means (9) advances the continuous material (M) along a path (8) through the chamber (3) and also maintains a vacuum seal at the entrance and exit zones (6,7). The support means (9) includes a backing roller (10) mounted adjacent the entrance and exit zones (6,7), an entrance sealing roller (11) positioned adjacent the entrance zone (6) and an exit sealing roller (13) positioned adjacent the exit zone (7).