Thin organic LbL (layer-by-layer) films with negatively charged surface were used as templates for biomimetic deposition of ZrO ₂ on Si wafers by hydrolysis of Zr(SO ₄ ) ₂ solution. The as-deposited ceramic layers were fully amorphous and were composed of the mixture of zirconia and zirconium sulfate. During transmission electron microscopy (TEM) examination, the amorphous ZrO ₂ crystallized almost instantaneously to tetragonal (t) ZrO ₂ under the electron beam. The ≤110 nm thick as-deposited layers were crack-free and adhered well to the LbL surface. Annealing at 500 °C led to complete crystallization of amorphous ZrO ₂ to nanocrystalline t-ZrO ₂ . Further heating to 900 °C resulted in transformation to monoclinic ZrO ₂ , complete removal of sulfur and twofold shrinkage of the ceramic layer thickness. Both the nanohardness and elastic modulus of the deposited zirconia layers were significantly improved following the heat treatments.