Potentialities of low-coherent tandem-type interferometry for optical monitoring of substrate temperature and bending during the metalorganic vapor-phase epitaxy (MOVPE) were demonstrated. Thickness of the growing layer was monitored as well. Absolute precision of temperature measurements on sapphire substrates during the MOVPE process was limited by the calibration accuracy and reaches +/- 1 degrees C. The accuracy of in situ measurements of the layer thickness was as high as 2 nm (RMS). Dramatic disagreements (in the range of 10-100 degrees C depending on pressure, gas flow, temperature etc.) between readings of the thermocouple fixed inside the susceptor and the actual substrate temperature were revealed. (C) 2008 Elsevier B.V. All rights reserved.