In this present work, nanocrystalline Co 2+ and Ta 5+ substituted barium bismuth niobate Ba0.5Co0.5Bi2NbTaO9 was synthesized by chemical process. Room temperature single phase, tetragonal structure was confirmed using X-ray diffraction (XRD) study. Average crystallite and particle sizes were found to be 33 nm and 40 nm, when analyzed through XRD and transmission electron microscopy (TEM) respectively. Field emission scanning electron microscopy (FESEM) was used for micro-structural investigation of samples sintered at 950?C for 4h. The investigation revealed that the material was exhibiting high dielectric constant value of 1017 at Curie temperature (Tc), 500?C when measured at 10 kHz. Impedance spectroscopy analysis showed that above 425?C, the material exhibited both bulk and grain boundary conductivities which were evidenced from FESEM studies. Density of states, minimum hoping distance, binding energy etc. were studied along with other electrical properties from impedance analysis. Hysteresis behavior was also investigated using polarization study.