Diffuser of an active liquid agent, for the treatment of a fluid environment, be it at the gaseous or liquid state, of the type including a container (1) of the active agent, closed by grid element apt to maintain in position the active agent and to allow the emanation of fluids of the same, the grid element being covered by a barrier film, peelable at the time of the first use to make operative the grid element, wherein the container (1) is closed by a single multilayer film (2, 3a, 3b) including at least one external barrier layer (3a) and at least another inner sealing layer (2) apt to maintain in position the active agent and to form the grid element, at the time of the first use of the container, following the simultaneous removal of the barrier film and of predefined portions of the sealing layer.
