Electrical breakdown field measurements on Polymethylmethylacrylate (PMMA) and a nano-composite of PMMA/Barium Titanate (BTA) by 10% wt are presented. The measurements were made using uniform field electrode configuration under high voltage DC. The electrodes were made of stainless steel, each having a Bruce profile, and diameter 25 mm. The measurements were made at room temperature (293 K) and liquid Nitrogen temperature (77 K). Using Weibull statistics it shows that both PMMA and the nano-composite have breakdown electrical field strengths much higher at 293 K than at 77 K. It has been shown that there was very marked improvement in the reliability of results for both compounds at 77 K over those at 293 K. The SEM micrographs have shown very distinct differences in the behavior of the nano-compound between 293 K and 77 K, PMMA also exhibit some clear differences.