LiNbO3 crystals with a variety of compositions were prepared by the vapor transport equilibration (VTE) technique. Crystals were characterized through the measurements of fundamental absorption edge, lattice parameters and the electric field required for ferroelectric domain switching. The techniques employed for characterization served as tools for the determination of the composition and homogeneity of the crystals. We discussed the Li diffusion mechanisms in LiNbO3 crystals at high temperature and found that the Li vacancy model is consistent with the experimental results for the VTE-grown LiNbO3 crystal. (C) 2002 Published by Elsevier Science B.V.