Abstract: An arrangement for measurement of temperature and thickness growth of silicon rods in a silicon deposition reactor employs a temperature measurement device located outside the reactor. Continuous temperature measurement and measurement of the thickness growth throughout the entire deposition process is achieved with a contactlessly operating temperature measurement device arranged outside the silicon deposition reactor in front of a viewing window. The temperature measurement device can be pivoted horizontally about a rotation axis by a rotating drive. The pivoting axis runs parallel to a longitudinal axis of the silicon rod, and the central axis of the temperature measurement device runs through the pivoting axis.