(Ba0.3Sr0.7)Mn-x(Ti0.9Zr0.1)(1-x)O-3 (x = 0.00, 0.013, 0.015 and 0.05) ceramics were prepared by solid state sintering route at the 1500 degrees C for 6 h in air. Effect of Mn substitution on the structure of Ba0.3Sr0.7(Ti0.9Zr0.1)(1-x)O-3 perovskite was investigated systematically. Dielectric and impedance spectroscopic studies were conducted to understand the electronic microstructure of the Ba0.3Sr0.7(-Ti0(.9)Zr(0.1))(1-x)O-3 ceramics. Sample with x = 0.05 showed the highest dielectric constant (epsilon(r) = 1826) and low dielectric loss (tan delta = 0.001) at 10 kHz, around the room temperature, while the sample with x = 0.00 showed good microwave (MW) dielectric properties (Qf(o) = 838 and epsilon(F) = 550). The impedance spectroscopic analysis confirmed the electrical homogeneity of the samples with x = 0.013, 0.015 and 0.05, where grain boundaries dominated the conduction mechanism. Similarly, the sample with x = 0.00 was found to possess both grain boundary and bulk resistive contributions. (C) 2015 Elsevier Ltd. All rights reserved.