High pure Sm(DPM)(3) (DPM = 2,2,6,6-tetramethyl-3,5-heptanedionato) powder was successfully synthesized from Sm(NO3)(3) and HDPM in ethanol/aqueous solution followed by reduced pressure distillation and recrystallization from toluene. This metal beta-diketonate complex used as precursor for metal-organic chemical vapor deposition (MOCVD) of Sm2O3 film has been characterized by elemental analyses, H-1-NMR spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA analysis), infrared spectroscopy and mass spectroscopic analysis. The thermal decomposition behavior of the complex is sensitive to the ambient gases and Sm(DPM)(3) is sufficiently stable after it being exposed to air for 30 days. The chemical bonds in the complex are decomposed in the sequence of C-O> SmO > C-C(CH3)(3) > C-C and C-H at elevated temperatures. At 400degreesC this complex thoroughly converts into Sm2O3 and Sm-2(CO3)(3) in air. The decomposition mechanism may be somewhat different at different operation conditions. (C) 2004 Elsevier B.V. All rights reserved.