A cap sterilization device has a sterilization chamber (101) with a cap inlet (106) and a cap outlet (108). Guide means (104) are arranged for guiding caps (102) through the sterilization chamber (101). The device also has a nozzle (110) for injecting a sterilant into the sterilization chamber (101) and at least two exhaust outlets (112 114) for evacuation of gases from the sterilization chamber (101).