TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The BET surface area of niobic acid is 10-300 (preferably 80-200) m2/g. The niobic acid is used in powder, tablet, pellet or extrudates having mechanical resistance of tablet/pellet or extrudates of niobic acid is 10-40 Nmm-1.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The alcohol is added in excess to the reaction mixture, with molar alcohol fatty acids ratio of 1.5-6. The water content of niobic acid is 5-25 wt.%. The niobic acid is calcined at 100-300degreesC for 1-3 hours. The niobic acid used in the reaction is 1-2 wt.%. The reaction temperature is 80-200 (preferably 120-170)degreesC. The pressure of reaction is endogenous and depends on the temperature and alcohol used. The reaction configuration uses batch reactors, continuous reactors of fixed bed and perfect mixture. The time of residence in the batch reactors is 60-300 minutes of reaction. The spatial time in the continuous reactions in relation to the fatty acids flow rate and volume of solid catalyst is 15-160 (preferably 30-120) minutes. Preferred Components: The free fatty acids are obtained from refining of vegetable oils (e.g. soy, rape, palm, canola, olive, babacu, peanut, coconut, castor, cotton and sunflower oils); disposals where free acidity is significant (e.g. used vegetable oils, rejects of industrial oils, animal fat and fat-enriched organic sewage). The free fatty acids are 6-24C carboxylic acids such as caproic, caprylic, capric, lauric, miristic, palmitic, palmitoleic, stearic, oleic, vaccenic, linoleic, linolenic, arachidic, gadoleic, arachidonic, behenic, erucic and/or linoceric acids. The alcohol is methanol, ethanol, propanol, isopropanol, butanol or isobutanol (preferably methanol or ethanol). EXAMPLE - A mixture of free fatty acids from refined palm oil consisting of lauric acid (1.2%), miristic acid (0.1%), palmitic acid (45.4%), oleic acid (40.5%) and linoleic acid (11.1%) and methanol at a molar methanol/fatty acids ratio of 3 to 1 was used as reagent. A sample of Niobia HY (RTM: powdered niobic acid) was calcined at 300degreesC for two hours in aerated muffle and added to the reaction mixture (test) (2 wt.%). After calcination, the powdered niobic acid presented a BET surface area of 170 m2/g. Another reaction mixture containing CBV-760 (RTM: zeolite with silica/alumina ratio of 60) (BET surface area 500 m2/g) was used as comparative. The reaction was conducted at 130degreesC in 500 ml Parr reactor with mechanical stirring of 500 rotation for a period of 60 minutes to give biodiesel. The biodiesel obtained (% yield) after 60 minutes in test/comparative was found to be 70/50).