Ba0.5Sr0.3TiO3 (BST 70/30) nanopowders have been prepared by the modified sol-gel method using barium acetate, strontium acetate and titanium isopropoxide as the precursor. The formation mechanism, phase evolution, and particle size have been investigated using TG/DTA, XRD, and SEM. The fine particles of the nano-powders calcined are homogeneous and well-dispersed and their narrow size distribution is about 15–25 nm. The as-formed gel was dried at 2000 C and then calcined in the temperature range 6500 C to 8500 C for crystallization. Phase evolution during calcination was studied using X-ray diffraction (XRD) technique which exhibited cubic crystal structure with perovskite phase. Sintering of the pellet was performed at 9500 C and the study on the dielectric relaxation and the ac electrical conductivity behavior of modified Barium titanate, Ba0.5Sr0.3TiO3 ferroelectric ceramic exhibit that these are thermally activated process.