Lanthanum acetylacetonate La(C5H7O2)(3)center dot xH(2)O has been used in the preparation of the precursor solution for the deposition of polycrystalline La2O3 thin films on Si(1 1 1) single crystalline substrates. The precursor chemistry of the as-prepared coating solution, precursor powder and precursor single crystal have been investigated by Fourier Transformed Infrared Spectroscopy (FTIR), differential thermal analysis coupled with quadrupole mass spectrometry (TG-DTA-QMS) and X-ray diffraction. The FTIR and X-ray diffraction analyses have revealed the complex nature of the coating solution due to the formation of a lanthanum propionate complex. The La2O3 thin films deposited by spin coating on Si(1 1 1) substrate exhibit good morphological and structural properties. The films heat treated at 800 degrees C crystallize in a hexagonal phase with the lattice parameters a = 3,89 angstrom and c = 6.33 angstrom, while at 900 degrees C the films contain both the hexagonal and cubic La2O3 phase. (C) 2010 Elsevier Ltd. All rights reserved.