There is described a unit for sterilizing a web of packaging material advanced along a given path, having, along a longitudinal portion thereof, a succession of pre-applied opening devices and adapted to be transformed in a plurality of sealed packages containing a pourable food product; the unit comprises a bath, containing a sterilizing agent in which the web with the opening devices is advanced, and an aseptic chamber connected to an outlet of the bath and housing drying mechanism for removing residual sterilizing agent from the web; the drying mechanism comprise an ejector located at a distance from the outlet of the bath and configured so as to direct a stream of air transversally to the web and onto the longitudinal portion of the web provided with the opening devices.