A series of liquid crystalline copolyesters, derived from 1,4-hydroxy-benzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), terephthalic acid (TA), and hydroquinone (HQ), were prepared; crystallization, melting and solid-state structure of the copolyesters were studied by using differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD). It was found that the variation of melting point of the copolyesters with increasing HBA mol % exhibits eutectic melting behavior at a constant mole ratio of HNA, and the extrapolated eutectic temperature decreases linearly with increasing HNA mol %. WAXD analysis of the copolyesters indicates that the d-spacing related to three-dimensional order increases first and then decreases with increasing HBA mol %. The increase of the d-spacing, consistent with looser packing of chains, leads to the reduction of melting point and most likely accounts for the eutectic behavior observed. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym, Phys 47: 2171-2177, 2009