Abstract. The full-text article is available at https://doi.org/10.1016/j.jallcom.2020.154611The ceramics (1−x)SrTiO3-x (0.93Bi0.5Na0.5TiO3-0.07Ba0.94Sm0.04Zr0.02Ti0.98O3) abbreviated as ((1−x) ST -x (BNT-BSmZT)) (x = 0, 0.1, 0.2, 0.3) were synthesized via solid-state sintering route. The phase structure, microstructure, electrical properties and energy storage performances of the outlined compositions were investigated using X-ray diffraction, electron microscopy, and dielectric measurement techniques. The X-ray diffraction results reveal structural phase transformation from a perfect cubic structure to a rhombohedral structure as the x value increased from 0 to 0.3. The submicron grain size of ∼0.71 μm was obtained for x = 0.1. The rest of the parameters such as breakdown strength (BDS), energy storage performance, charge-discharge efficiency (η), discharging time, dielectric loss and electrical conductivity were observed to be affected by the homogeneous, compact microstructure and grain size. Herein we report an innovative ST-based lead free ceramics capacitor with the highest breakdown strength (BDS) of 420 kV/cm, an impressive recoverable energy density (Wrec) of 1.93 J/cm3, simultaneously with high efficiency (η) of 80.0%, moreover, low dielectric loss, low electrical conductivity ∼4.7 × 10−8 S/m at 100 °C and fast discharge time (∼0.18 μs) in x = 0.1. Our findings in this work suggest that the obtained ceramics system might be a promising candidate for pulsed power technology.