The formation of porous anodic TiO2 with square cells and holes based on the modification of a lattice of holes by pretexturing using nanoimprinting is described. A Ti plate with an ordered array of shallow concaves in a square lattice prepared by nanoimprinting using a mold was anodized in an electrolyte containing fluoride ions. The shallow concaves in the Ti plate acted as starting sites for hole development at the initial stage of the anodization, and generated anodic porous TiO2 with square cells and holes originating from the close packing of the uniform-sized cells in the two-dimensional space. (C) 2016 The Electrochemical Society. All rights reserved.