Abstarct: In this thesis, barium hexaferrite (BaFe12O19) and the nanocomposites BaFe12O19/GO and BaFe12O19/rGO with different contents of graphene oxide (GO) and reduced graphene oxide (rGO) were synthesized via the self-combustion method. Moreover, the simultaneous doping of nickel (Ni+2) and zinc (Zn+2) ions into the crystal structure of barium hexaferrite and its composite with GO were investigated in terms of their structural, morphological, magnetic, optical, and dielectric properties. X-ray diffraction (XRD) patterns confirmed the hexagonal crystal structure for all samples. FESEM images revealed a reduction in particle size and improved uniformity in the nanocomposites and doped samples. EDX analysis and elemental mapping also confirmed the successful formation of the nanocomposites. Magnetic studies using a vibrating sample magnetometer (VSM) and SQUID showed that the incorporation of GO and Ni+2/Zn+2 doping improve the saturation magnetization and reduces the coercivity. The ZFC–FC measurements indicated the presence of complex magnetic features such as spin-glass states in some samples. All samples exhibited ferrimagnetic behavior, which is consistent with the crystal structure of barium hexaferrite. Optical studies revealed a decrease in band gap for the GO/rGO-containing samples, attributed to enhanced light absorption in the visible region. The results of this study demonstrates that compositional and structural engineering in BFO/GO-baxsed and doped nanocomposites can provide promising candidates for applications in magnetic sensors, electromagnetic wave absorbers, and energy storage devices.