###### Abstract
By introducing conductive fillers inside the polymer matrix, a lightweight conductive material with electromagnetic interference shielding properties can be obtained [10; 11]. The obtained epoxy composite materials demonstrated high shielding reflection of EM waves of microwave range. However, in order to obtain the materials with high absorption it is necessary to reduce the electrical conductivity of the filler and thus reduce the reflection of the electromagnetic wave. The most promising absorbent materials, according to technological, operational, and economic criteria, are those originating from a component exhibiting electrical conductivity (nanocarbon materials) that are enhanced by a magnetic component (spinel ferrites). Nanosized spinel ferrites (MFe\({}_{2}\)O\({}_{4}\), where M = Co\({}^{2+}\), Ni\({}^{2+}\), Zn\({}^{2+}\), etc.) are effective in EMR absorption applications as a consequence of their elevated saturation magnetization and magnetic losses, which include hysteresis loss and eddy current loss [15]. Ferrites exhibit several dielectric and magnetic resonances that beneficially impact EMR absorption. The incorporation of carbon materials (such as graphene nanoplatelets, graphene oxide, and carbon nanotubes), owing to their excellent properties (i.e., being lightweight, having high corrosion resistance, and superior electrical and thermal properties) allows for the development of materials with tuneable electric/dielectric properties for EM shielding absorption [16]. However, these materials often exhibit strong surface reflection, inevitably causing the secondary reflection of EM waves. In spite of the effective composition of components, providing the material with the necessary higher electromagnetic interference (EMI) absorption losses, reflection losses concurrently increase. Our preliminary studies have indicate that the development of nanocomposites, incorporating a conductive element modified by a magnetic component, demonstrates enhanced efficiency in absorbing electromagnetic waves within the microwave spectrum. Thisheightened effectiveness is particularly noticeable at optimal ratios of permittivity and permeability, outperforming components solely relying on pristine magnetic ferrite. [17]. Substituted ferrites enable the control of both magnetic permeability and magnetic losses in the microwave region. Therefore, the use of substituted ferrites (NiZn)\({}_{1-x}\)Mn\({}_{x}\)Fe\({}_{2}\)O\({}_{4}\) is relevant for creating EM-absorbing materials [18; 19]. Additional mechanisms for dissipation of electromagnetic energy in the microwave range with polymer-conductor systems have also been shown to be connected with polarization effects arising due to interphase interaction of the components [20; 21]. It is well-known that the creation of polymer composites allows for improved manufacturing, enhanced performance parameters, and, superior functionality for such materials. Epoxy resins (ER) are widely used as polymer matrices due to their excellent mechanical properties, chemical and heat stability, antibacterial properties, strong adherence, and low contractility [22; 23]. Meanwhile, the introduction of fillers in the epoxy resin that interact with microwave electromagnetic radiation can improve the impedance matching between polymer composites and the environment and cause greater polarization of the interface in the composites [24; 25]. The goal of this research was to create new potential nano-sized fillers based on substituted (NiZn)\({}_{1-x}\)Mn\({}_{x}\)Fe\({}_{2}\)O\({}_{4}\) ferrites anchored on the surface of multi-walled carbon nanotubes that would be dedicated as active fillers of the epoxy matrix interacting with elec-tromagnetic radiation in the microwave ranges.