Barium hexaferrite with nominal chemical composition BaMnZn2Fe10O19 has been synthesized by sol-gel method, using polymethyl methacrylate (PMMA) as a template. Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD) were used for approving the formation of barium hexaferrites. In addition, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were performed to investigate the structural and morphological properties of BaM. The dielectric properties were studied by impedance measurements as a function of frequency (in the range 0.1 Hz-1 MHz). The XRD patterns confirmed the formation of single-phase magnetoplumbite with crystallite size around 73 nm. The results of dielectric parameters and conductivity measurements showed three regions with different behaviors in electrical conduction mechanism.