Dielectric liquids (edible/non-edible) are alternative innovative for mineral oil coolant commonly used in distribution and power transformers. In this work an attempt is made to improve the properties of pongamia pinnata non edible oil by esterification carried out by changing different parameters such as temperature, time and amounts of catalyst. After modification of pongamia pinnata non-edible oil different properties such pour point, flash point, moisture content, viscosity, density, acid value, Breakdown Voltage, Dielectric constant, Dielectric dissipation and Oxidation stability are determined by standard methods and compared with the standard value of mineral oil used for the transformer. The Acid value, breakdown voltage, Pour point and Flash point are found to be 0.154 mg of KOH/ g of Oil, 71.1 kV, -9 0C and 167 0C respectively which are within the comparable range. Hence, this has shown the potential of pongamia pinnata non-edible oil as a dielectric fluid and can be used in the place of standard mineral oil used as a coolant in the transformer.