A device (a probe) intended to be used exclusively to monitor tissue or body temperature during hyperthermia treatments. Depending on the kind of hyperthermia system it is used with, e.g., ultrasound, radio-frequency (RF) or microwave, this probe is shielded in such a way that its operation is not affected by the energy from the hyperthermia applicator(s) in use during the treatment. This is a reusable device.