A double layer of single domains with opposing polarizations has been formed on bothcfaces by rapid thermal annealing of proton‐exchangedz‐cut LiTaO3at above the Curie temperature. The formed top single‐domain layers have inward‐directed polarization and the single‐domain layers underneath have outward‐directed polarization. The domain structure development for an annealing range from 2 s to 10 min has been investigated. The results are discussed in relation to recently proposed models for the domain‐inversion mechanisms in LiTaO3and LiNbO3. ©1995 American Institute of Physics.