The invention relates to a freeze-dryer product sensor (1). The freeze-dryer product sensor (1) comprises a transducer (13) for sensing a product parameter and an RFID unit (14). In a storage unit (28) of the RFID unit (14) at least one characteristic parameter (29) specific to the freeze-dryer product sensor (1) is stored.According to the invention the freeze-dryer product sensor (1) comprises only one single antenna unit (3), which leads to a reduced effort in constructing the freeze-dryer product sensor (1).The inventive freeze-dryer product sensor may be employed in a drying vessel. The invention also relates to a method for operating such a freeze-dryer product sensor.