The work presents the results of studying the structure of binary liquid nanocarbon systems obtained by mixing hydrosol of detonation nanodiamond and aqueous dispersions of single layer graphene oxide flakes. We studied size and space distribution of nanocarbon clusters formed upon interaction of the components in aqueous media by mutually complement methods of small-angle X-ray and neutron scattering. The formation of small secondary agglomerates of nanodiamond particles on the surface of graphene oxide flakes was concluded and supported by the data of transmission electron microscopy from dried samples. The observed effect can significantly modify the structure of nanocarbon composites formed of nanodiamond and graphene oxide. The structural features of binary dispersions detonation nanodiamond–graphene oxide should be taken into account at the preparation of the conductive composites of reduced graphene oxide for energy storage systems.