Undoped barium titanate ceramic samples with high density were produced by using both high purity hydro-thermally synthesized and oxalate-derived powders. Sintering temperature was varied in the temperature range 128$0^{circ}C$-140$0^{circ}C$ to control the average grain sizes of the samples. Electrical breakdown test was performed at two different temperature with 3$0^{circ}C$(below Tc) and 15$0^{circ}C$ (above Tc) for samples immersed in silicon oil bath using 60kV dc power supply. From the experimental results at below and above Curie temperature the grain size and thickness dependence of electrical breakdown strength for BaTiO3 ceramics was presented and breakdown behavior was also studied.