This work investigated the electrical properties of Nb5+ (0.0-1.0 mol%) doped with Ba0.90Ca0.10Zr0.10-Ti0.90O3 while adding 1 mol% of Ba0.90Ca0.10Zr0.10Ti0.90O3 seeds. The mixed powder was ball milled for 24 h, calcined and sintered at 1200 degrees C for 2 h and 1450 degrees C for 4 h, respectively. The XRD patterns of the ceramic samples were investigated by X-ray diffraction. The electrical properties of ceramics were measured and the results indicated that all samples show a pure perovskite phase with no secondary phase. Density and average grain size values were in the range of 5.60-5.71 g/cm(3) and 12.62-1.86 mu m, respectively. The highest dielectric constant, epsilon(r) at room temperature (1 kHz) was 4636 found at 1.0 mol% Nb. The dielectric loss, tan delta was less than 0.03 for all samples at room temperature (1 kHz). Other electrical properties, P-r, d(33) and k(p) values were decreased with Nb doped relates to the decreasing grain size in BCZT ceramics. Moreover, the degrees of phase transition diffuseness and relaxation behavior were observed in the higher Nb doping. (C) 2015 Elsevier Ltd. All rights reserved.