In this manuscript, We have reported the synthesis and characterization of Mg-doped and undoped BCTO ceramic (Bi2/3Cu3-xMgxTi4O12, x=0,0.05,0.1,0.2) sintered at 1173 K for 8 h, which have been prepared by the semi-wet path. Single-phase formation of ceramic was approved by the XRD pattern. The Microstructural properties were studied by TEM and AFM. The samples were characterized by dielectric and impedance spectroscopic properties. The dielectric constant (εr) was calculated to be 3024 for BCTO ceramics at 423 K and 100 Hz. The tangent loss (tan δ) value was calculated to be 0.45 for BCTO ceramic at 423 K and 10 kHz. The internal Barrier Layer Capacitance (IBLC) mechanism was responsible for the high value of dielectric constant. XPS spectroscopy confirmed the oxidation state of the ceramic. It was observed from Impedance and modulus studies that there was the existence of the Maxwell-Wagner form of relaxation in the ceramics.