Abstract: The invention relates to an insertable electrode device (DEI) for metal electrowinning processes, said device being non-polluting since it does not generate acid mist or other gases. The principle is based on an oxidation half-cell reaction occurring inside the DEI, together with the reduction half-cell that occurs in the metal electrowinning cell using same. The DEI does not generate gases and therefore does not emit acid mist into the environment. The DEI replaces current anodes and permits oxidation reactions to occur below the energy threshold of electrolysis of water, thereby preventing the electro-generation of gaseous oxygen, which is the main cause of acid mist.