Small-angle neutron scattering (SANS) was applied for the structure characterization of detonation nanodiamond (DND) aqueous suspensions with a positive, zeta potential. The contrast variation technique (based on mixtures of light and heavy water) was used to study the structure of DND particles and their clusters in solutions. The results were compared with the data of the previous similar experiments for DND suspensions with a negative zeta potential. The experimental range of the neutron scattering contrast in the system was extended to maximally possible by starting with the initial concentrated suspensions separately prepared in light and heavy water. (C) 2016 Elsevier B.V. All rights reserved.