The subject is focused on the methods for the characterization of the phase composition and structure of the nanomaterials. The subject will enable to understand the significance of the X-ray diffraction analysis for the characterization of the nanomaterials. The initial lectures are oriented on the description of the materials´ structure, the terms connected to the symmetry of the crystal structures and crystallochemistry will be defined. Next part of the lectures will provide the insight into the origin and the characteristics of the X-ray irradiation, its interactions with the matter. Information about the X-ray diffraction techniques, the X-ray diffractometers construction and the individual functional attachments will be the part of next block of the lectures. The application of the X-ray diffraction analysis for qualitative and quantitative phase analysis will be described. In the last block of the lectures, the utilization of the diffraction methods for the structural characterization of the nanomaterials will be described.