A decontaminating apparatus (1) for decontaminating the mouth (2b) of a parison or a container (2) made of thermoplastic material, comprising: a concave shell (3) configured to be applied onto the mouth (2b) of the parison or container (2) in such a manner as to enwrap at least partially the neck (2a) of the parison or container (2) so as to delimit a volume of treatment (4) of the neck (2a) that leaves out a bague (2c)； a supplying circuit (20) configured to supply in the volume of treatment (4) ozone or a plasma, that is a globally neutral ionized gas, immersed in a carrier that is constituted by vaporized hydrogen peroxide.
