Most power transformers used petroleum-based oil or so-called mineral oil as insulation. Power transformer oil functions not only as electrical insulation and cooling medium but also to suppress corona and arcing. Over the years, power transformer oil has been widely used because of its high dielectric field strength, low dielectric losses, and long-term performance. However, petroleum-based power transformer oil is nonbiodegradable and non-renewable. A serious spill could contaminate soil and water. As a non-renewable source, depletion of the source will further increase the price. These have encouraged researchers to look for alternative power transformer oil for better sustainability. Palm-based oil has been seen as a potential substitute, because, it is environmentally friendly, biodegradable and renewable. However, a lot of studies need to be carried out before it can be used as alternative power transformer oil commercially. Thus, this work has been carried out to investigate several electrical and physical properties of palm-based transformer oil, such as breakdown voltage, partial discharge characteristics, kinetic viscosity, and flash point. The effect of ageing on electrical properties of the palm-based oil has also been investigated. Two types of palm-based oil, namely Palm Fatty Acid Ester (PFAE) and Refined, Bleached, Deodorized Palm Oil (RBDPO) have been selected in this work. As a comparison, the commercially available soy-based biodegradable oil is also investigated for assessment and further analysis purpose. The results revealed that PFAE and RBDPO have great potential as power transformer insulation because of their good insulating characteristics as commercially available biodegradable oil.