A sterilizer comprises a sterilization chamber (1) with a test device (2) for testing the effectiveness of a sterilization process. The test device (2), in turn, comprises a test element (3) with a sensor (4) for measuring at least one parameter, and cooling mechanism (5) for cooling the test element (3). The test device (2), as a whole, is completely accommodated within the interior (8) of the sterilization chamber (1)
