Properties of layered composites with carbon nanotube (CNT), GnP, Fe3O4 nanoinclusions, and hybrid composites with these nanoinclusions were investigated in the wide frequency range (from 20 Hz to 2 THz). All investigated composites (except with single Fe3O4 inclusions) are above percolation threshold. The strong enhancement of microwave and terahertz radiation absorption is observed in hybrid composites in comparison with composites with single inclusions. The synergy effect is discussed in terms of the complex impedance and the distribution of relaxation times. At low temperatures (below 200 K), the electrical conductivity of all hybrid composites follows the tunneling law model and the lowest potential barrier was estimated for composites with CNT inclusions. The best thermal properties are observed for composites with CNT inclusions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48814.