A considerable effort has been lately invested in the improvement of optical-based in situ methods for the real-time control of metalorganic chemical vapor deposition (MOCVD) processes. We present a novel approach combining in situ X-ray diffraction and spectroscopic ellipsometry applied during the MOCVD of GaN/AlGaN superlattices. We demonstrate that the combination of surface- and bulk-sensitive in situ characterization techniques yields complementary but consistent information about the periodicity and the layer composition of the multilayer structures. (C) 2007 Elsevier B.V. All rights reserved.