Ailanthus excelsa seed oil is identified as minor seed oil from forest origin for biodiesel production. The seed oil was initially characterized for various physico-chemical properties following standard protocols. The extracted oil was further refined and transesterified to produce biodiesel. The prepared biodiesel was evaluated for fuel properties such as the iodine value, free fatty acids, phosphorous content, flash point, cloud point, pour point, viscosity at 40 degrees C, oxidative stability at 110 degrees C, density, and trace metals. The properties were compared with international specifications and it was found that the oxidative stability of the prepared biodiesel was better compared to most of the biodiesels reported.