High temperature X-ray diffraction, thermal expansion and Raman spectroscopic measurements have been conducted to investigate the structural behavior of nearly stoichiometric LiNbO3. Abnormal thermal expansion has been observed within the temperature range of 1021-1373 K. The mechanism responsible for the abnormal phenomena and the structure deformation has been identified as the competition between the thermal vibration in the x-y plane and the antiphase motion along the z-axis of the [NbO6] framework as a function of temperature through the analysis of the temperature dependent Raman spectra. (C) 2010 Elsevier B.V. All rights reserved.