TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Acid: The organic acid is selected from phosphoric acid, oxalic acid and citric acid.Preferred Process: The solidified gum or phospholipids contained in the oil is removed from the oil, by centrifugation operation. The raw material is transesterified in the presence of an alkaline catalyst. Centrifugation processing and/or heating under reduced pressure is performed after removing heavy liquid from the raw material oil. EXAMPLE - Cured palm oil having an acid value of 10, an iodine number of 45, a flash point of 230degreesC, a water content of 5% and gum and phospholipids of 0.2%, was produced. Oxalic acid (wt.%) (0.5), was added to the raw material oil at room temperature, and acid treatment was performed for one hour. A brown solid substance appeared. The raw material oil was heated to 95degreesC and the solid substance was removed by centrifugation. The raw material oil was heated to 140degreesC, and an absolute pressure of 0.8 mmHg was applied for 15 minutes. The resulting oil was cooled to 65degreesC and used for transesterification. Potassium hydroxide as catalyst and methyl alcohol (11 weight parts) having a purity of 99.5% were added to the oil (100 weight parts). The resulting raw material oil was reacted for 15 minutes and separated to obtained a fatty acid methyl ester layer (light liquid) and a glycerol layer (heavy liquid). The fatty acid methyl ester layer was passed to a column filled with activated clay (1 weight part), and fatty acid methyl ester layer was centrifuged and solid substance separation was performed. The resulting liquid was heated at 65-75degreesC, then heated under reduced pressure of 100 mmHg for 20 minutes, and a bio-diesel fuel composition was obtained. The obtained composition had a conversion ratio of 99.6%, a cetane number of 58, 90% a distillation temperature of 340degreesC, a flash point of 135degreesC, a pour point of 8.8degreesC, a dynamic viscosity of 5.62 m2/s at 40degreesC, a specific gravity of 0.866, an acid value of 0.2 mgKOH/g, a water content of 0.02%, an alcohol content of 0.007, and phosphorous of 5 m/k.