A conventional solid phase reaction method was followed to prepare (1−x)BaTiO3-xCaTiO3 based ceramics with content fractions ranging from x = 0.00 to 1.00. Phase segregation was observed when x exceeded 0.10. DC breakdown voltage (DC-BDV) abruptly changed at x = 0.30 and 0.85. Furthermore, the DC-BDV values of insoluble compositions (x = 0.30−0.85) were much higher than those of solubility limit (x = 0.20 and 0.90). Results obtained by investigation of the amount of absorbed current and the dependence of the rate of voltage increase for DC-BDV and AC-BDV confirmed the formation of space charge in insoluble compositions. This suggests that the dependence of the DC-BDV value for (1−x)BaTiO3-xCaTiO3 based ceramics was affected by the formation of space charge.