The reaction between hafnium tetrachloride and neopentyl alcohol in the presence of ammonia lead to hafnium oxoneopentoxide (1). 1 was characterized by FT-IR, H-1 and C-13 NMR. Single-crystal X-ray diffraction identified it as a trinuclear oxo species Hf-3(mu(3)-O)(mu(3)-ONep)(mu-ONeP)(3)(ONeP)(6). The oxoneopentoxide has been used as precursor for the growth of HfO2 films by pulsed liquid injection MOCVD. The influence of deposition temperature (320-750degreesC) on film growth rate, roughness and microstructure was studied and compared with the conventional Hf(thd)(4) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) precursor. Depending on the deposition temperature, amorphous, polycrystalline or epitaxial films can be obtained on sapphire (R-plane) substrates. The film growth rate was independent of the deposition temperature in the range 350-750degreesC. (C) 2004 Elsevier B.V. All rights reserved.