Yellow oleander (Thevetia peruviana Schum.) seed oil has been investigated to produce biodiesel. Transesterification of the oil to biodiesel was carried out in methanol by batch reaction using a heterogeneous catalyst derived from the trunk of Musa balbisiana Colla (one variety of banana plant). 96 wt.% of the oil is converted to biodiesel at 32 degrees C in 3 h. The wt.% composition of the biodiesel is methyl oleate 43.72, methyl palmitate 23.28, methyl linoleate 19.85, methyl stearate 10.71 and methyl arachidate 2.41. Fuel properties conform to standards set for ASTM D6751, EN 14214, BS II and BS III, and in certain aspects better. The biodiesel is free from sulfur and has exhibited a high cetane number of 61.5. (C) 2011 Elsevier Ltd. All rights reserved.