In order to improve the quality of neutron supermirrors periodic multilayers of various periods were prepared. The reflectivity properties of these systems were investigated using neutron and X-ray reflectometry. The obtained experimental results were compared with the calculated ones. The deviations from the proposed structure and calculated scattering length densities were investigated. In first approximation, the results proved the main features of the calculations. The roughness of different interfaces was also investigated. (C) 2013 Elsevier B.V. All rights reserved.