A hybrid nanomaterial composed of detonation nanodiamonds-multi-walled carbon nanotubes (DND-CNT) in powdered form and the form of stable recoverable water nanofluid was obtained. The ability to obtain a hybrid material in the form of powder, as well as in the form of an aqueous suspension opens the way for the creation of new composite materials based on metals and polymers, as well as new types of nanofluids. Particle size in water suspension was investigated by dynamic light scattering (DLS) method and has been shown that while the original DND was agglomerates with the particle size about one 1.1m, the particles size of a hybrid material in water suspension was 40-60 nm. Such result was achieved by growing multi-walled carbon nanotubes on the surface of nanodiamonds aggregates coated with a metal catalyst using catalyst chemical vapor deposition (CCVD) method for nanotubes growth. The resulting nanomaterial is a powdered hybrid material obtained based on a scalable technology. The measured electrical conductivity of the water suspension amounted to 35 mu S/cm what is 6 times higher than the electrical conductivity of the pure distilled water. (C) 2020 Elsevier Inc. All rights reserved.