Abstract: An apparatus for calibration of temperature sensors, comprising a cavity (2) for receiving a sensor (10) to be calibrated, a heat-transferring medium (5) for surrounding the sensor in the cavity, and a means for heating/cooling of the medium to a desired temperature. The cavity (2) receives at least one sensor-surrounding thin-walled calibrator body (3) which is made of a pliable material having a high thermal conductivity and which defines a volume (4) which is filled of a heat-transferring medium, the calibrator body (3) having an inner wall (8) defining at least a part of an inner opening (9) for receiving at least one sensor (10), and being arranged to be subjected to a pressure influence to bring the opening-defining wall (8) of the calibrator body into tight-fitting abutment against the sensor (10) or sensors.