In this work, an attempt has been made to characterize, isolate and elucidate the structure of unusual fatty acid in the seed oil of Aegle marmelos Corre. Further, this nonedible seed oil is screened for its bio-diesel or industrial feedstock property. The Aegle marmelos Corre seeds yielded 49.0% oil. The seed oil contains 12.5% of 12-hydroxyoctadec-cis-9-enoic acid (ricinoleic acid) along with other normal fatty acids. The identification and characterization was supported by FTIR, (1)H NMR, (13)C NMR, MS, GC analysis and chemical degradation technique. A good agreement is seen between the calculated and experimental results of iodine value (IV) and saponification value (SV). The prominent parameters of bio-diesel such as cetane number (CN), lower heating value (LHV) and higher heating value (HHV) are deployed to envisage the quality of oil for use as bio-diesel. This seed oil is nonedible and is found to be the alternative feed stock for the production of bio-diesel since it convenes the major specifications of bio-diesel. The bio-diesel property of fatty acid methyl esters (FAMEs) of this seed oil is compared with other bio-diesels. (C) 2010 Elsevier Ltd. All rights reserved.