Due to concerns regarding energy security, fuel cost, and the environment, straight and processed vegetable oils are being considered as part or full replacement of diesel fuel in compression ignition engines. The lower heating value of a candidate fuel is an important characteristic used in energy release estimation. In this work, a convenient method of estimating the heating values of straight and processed vegetable oils based on the bond energies of their fatty acid/methyl ester constituents is proposed. The estimated lower heating values of 17 different straight vegetable oils are on the order of 37 MJ/kg and for 15 different processed fuels on the order of 38 MJ/kg. The accuracy of estimations when compared with the available experimental data is observed to be within 3%. © 2009 American Chemical Society.