Abstarct: In this study, (CFO)x- (BTO) (100-x), (MFO)x- (BTO) (100-x) and (NFO)x- (BTO) (100-x) (x = 10, 20, 30, 40, 50) nanocomposites were synthesized using a sol-gel process. The structural, morphological, optical, magnetic, and dielectric properties of the samples were investigated. According to the X-ray diffraction data, all composites exhibit the tetragonal phase for BTO and the spinel phase for ferrite. FTIR spectroscopy confirmed the presence of both BTO and ferroelectric phases. FESEM images showed that as the ferrite concentration increased, the particles became more agglomerated and irregular in shape. The hysteresis loops (M-H) measured at room temperature indicates an increase in saturation magnetization with an increase in the ferrite content. The dependence of the band gap on ferrite content was also studied using UV-visible spectra, which showed that the band gap energies are in the range of 1.66-2.71 eV. With an increase in ferrite content, the dielectric constant decreases and the dielectric tangent loss increases. Additionally, investigation of the Nyquist plots showed with increase in the ferrite phase in the composites electrical resistivity increases. In the following section of the thesis, CMFO-BTO, NCFO-BTO and NMFO-BTO nanocomposites were synthesized using the sol-gel method, and their structural, morphological, optical, magnetic, and dielectric properties were investigated. The X-ray diffraction patterns indicate the presence of a tetragonal phase for BTO and a spinel phase for the ferrite as before, which is consistent with the results from FTIR spectroscopy. FESEM images revealed particles with polygonal shape, agglomerated and heterogeneous. The energy bandgap of these nanocomposites was found to be in the range of 1.45 eV to 1.82 eV. The hysteresis loop results demonstrated that the NMFO-BTO composite exhibits a thin hysteresis loop, indicating soft magnetic behavior. Additionally, the highest saturation magnetization and remanent magnetization were observed in the CMFO-BTO sample. The dielectric measurements showed that the CMFO-BTO sample has the highest dielectric constant and the lowest loss factor. Moreover, according to the Nyquist plot, the NMFO-BTO sample has the highest resistivity.