Mesoporous zirconia (ZrO 2 ) thin films were prepared by dip-coating via Pluronic P123 templated sol–gel route. ZrOCl 2 ·8H 2 O was used as zirconium (Zr) precursors. Annealing of as-coated ZrO 2 thin films is important in order to stiffen the respective films and to remove the Pluronic P123. The mesoporous structure and crystallite size of ZrO 2 were characterized systematically by field-emission scanning electron microscope (FESEM), both low- and wide-angle X-ray diffraction, thermal analysis technique and Brunauer–Emmett–Teller method. At annealing temperature of 400°C, amorphous ZrO 2 was transformed into tetragonal phase of ZrO 2 (t-ZrO 2 ). At 450°C, t-ZrO 2 and monoclinic phase of ZrO 2 (m-ZrO 2 ) were obtained. By altering heating rate during annealing, volume fraction of t-ZrO 2 and m-ZrO 2 was changed. FESEM images showed that disordered mesostructures of ZrO 2 were formed after annealing. The surface area of mesoporous ZrO 2 obtained ranges from 54.33 to 93.39m 2 /g.