MgO{1 1 1} and {1 0 0} crystals are widely used as substrates for thin film growth, in many different areas of research such as superconductors, and other oxide, metal and nitride films, multilayers and superlattices. Since the quality of the thin film can be strongly dependent on that of the substrate, the optimal film properties will only be fully conceived if the substrate is well characterized in advance. The goal of this work was to create a characterization method which was inexpensive, fast, efficient, and of course nondestructive, for assessing imperfect metal-oxide substrates. X-ray diffraction (XRD) was chosen because of its low cost, simplicity, nondestructiveness, and the fact that we have access to many different parameters using the same instrument. The miscut of the MgO crystals studied herein were characterized with a high resolution of 0.01 degrees. The number of domains, their distribution and their size were characterized by omega-phi maps and topography measurements. In this case, atomic force microscopy (AFM) was found to be more appropriate for assessing roughness than X-ray reflectivity measurements.