In-situ energy-dispersive X-ray diffraction performed at the BESSY and HASY-LAB synchrotron facilities was used to observe sulfur pressure dependent growth paths for the formation of CuInS(2) thin films from Cu-rich metallic precursors. CuInS(2) can form directly from the intermetallic phases, through binary sulfides or via CuIn(5)S(8). Particular attention is given to the latter reaction sequence, typical of rapid thermal processing (RTP), with complementary EDS and SEM analysis. (C) 2008 Elsevier B.V. All rights reserved.