The crystal structure of In2S3 thin films obtained by the chemical vapor deposition method from the volatile complex compounds indium(III) isopropyl xanthate and indium(III) diethyl dithiocarbonate was studied by synchrotron radiation diffraction. High photon beam intensity (3 x 10(10) photons/mm(2) . s) and the high angular resolution (0.02 degrees) of the reflexes made it possible to study weak reflexes to analyze the phase composition of samples in more detail, to determine the size of the particles (the size of coherency), and to evaluate the stress at the microscopic level. It is shown that for indium sulfide films deposited at T=230 degrees C, the structure is cubic (alpha-In2S3). For deposition temperatures T=250 degrees C and higher, the structure is tetragonal (beta-In2S3). During annealing an alpha-beta phase transition was observed at T=400-420 degrees C. For samples deposited at 430 degrees C, a splitting of the (5,0,15) reflex was observed, which can be assigned to monoclinic or hexagonal distortions of the lattice. (C) 1998 Academic Press.