Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray powder diffraction (XRD) studies on nanocrystalline TiO2 powders and thin films are presented. The size, shape (mostly exposed faces), and ordering of the TiO2 anatase particles in the nanocrystalline films are discussed. The use of the topochemical approach, which considers the properties of (nanocrystalline) solids in terms of crystallographic features of (nano)crystals is suggested. The surface area of sensitizer [bis(4,4‘-dicarboxy-2,2‘-bipyridine)bis(thiocyanato)]ruthenium(II) [abbreviated as (cis-Ru(dcbpy)2(NCS)2] on the semiconductor surface for the different types of anchoring is estimated on the basis of single-crystal X-ray diffraction studies of the esterified form of the complex.