Abstract: The invention relates to a process and apparatus for the treatment of bulky fibrous webs, derived at least partially from thermoplastic fibres, so as to impart cohesion to the webs. The process involves passing the webs between at least one pair of rotating cylindrical metallic electrodes, of which one is connected to a high frequency generator and the other is connected to earth, the web being compressed between the electrodes and being driven by them. One of the electrodes is covered with a layer of dielectric material having a smooth surface, and the discharges produced between the electrodes are partial discharges (or glow discharges), the path of which extends over only a part of the gap between the electrodes, starting from the electrode covered with dielectric material and extending to near the surface of the other electrode.