Abstract: The invention concerns the treatment of porous structures such as cross-linked foams, woven or nonwoven, to make them electrically conductive by depositing polymers. The device enables, in a chemical reactor, to perform the activating treatment directly through non-reeled off blocks or rolls of porous structures, the treating fluids of the successive steps being made to circulate inside said blocks or rolls, via a perforated rotary mandrel whereon they are pressed. Said device enables to activate efficiently the structures, which may be metal-coated or not, and are particularly designed to be used as electrodes for liquid effluent electrolysis, of detectors and traps of organic or biological molecules, electrode supports for electrochemical generators, catalyst supports, filtering media, acoustic insulants, electromagnetic, nuclear and antistatic protection structures, heat exchangers and the like.