A device for carrying out a cosmetic method or treating skin ageing and the method comprising the following steps: a) connecting an electronic device, able to generate high frequency electric current waves having a distorted sinusoidal wave form by the presence of harmonics, to one or more electrodes of essentially laminar shape; b) applying said one or more electrodes on the skin surface in the area to be treated; c) activating said electronic device in order to transfer said current waves to said one or more electrodes and to maintain said device activated for a predetermined time; d) deactivating said device and removing the electrodes from the contact with the treated area.