A simple and green method for the determination of the iodine number in biodiesel is proposed based on the Friedmann procedure for oils and fats adapted for biodiesel. The reagent solutions used are prepared in water with the exception of the standard iodine and the biodiesel solutions that are dissolved in ethanol 96 %. The method was compared with the procedure recommended by the norm EN 14111, which is essentially the Wijs method. Biodiesel derived from several oils and fats were analyzed using the two methods. A statistical comparison between them shows that both offer equivalent results and precision. Copyright © 2010 by ASTM International,.1477 146156Shay, E.G., Diesel fuel from vegetable oils: Status and opportunities (1993) Biomass Bioenergy, 4, pp. 227-242Rinaldi, R., Garcia, C., Marciniuk, L.L., Rossi, A.V., Schuchardt, U., "Síntese de Biodiesel: Uma Proposta Contextualizada de Experimento para Laboratório de Química Geral (2007) Quim. Nova, 30, pp. 1374-1380Ma, F., Hanna, M., Biodiesel Prodution: A review (1999) Bioresour. Technol, 70, pp. 1-15Demirbas, A., Relationships derived from physical properties of vegetable oil and biodiesel fuels (2008) Fuel, 87, pp. 1743-1748Ramos, J.R., Fernández, C.M., Casas, A., Rodríguez, L., Pérez, Á., Influence of fatty acid composition of raw materials on biodiesel properties (2009) Bioresour. Technol, 100, pp. 261-268Encinar, J.M., González, J.F., Rodrigues-Reinares, A., Ethanolysis of used frying oil. biodiesel preparation and characterization (2007) Fuel Process. Technol, 88, pp. 513-522Schuchardt, U., Sercheli, R., Vargas, R.M.J., Transesterification of vegetable oils: A review (1998) J. Braz. Chem. Soc., 9, pp. 199-210Knothe, G., Analyzing biodiesel: S tandards and other methods (2006) J. Am. Oil Chem. Soc, 83, pp. 823-833Knothe, G., Structure indices in FA chemistry. How relevant is the iodine value? (2002) J. Am. Oil Chem. Soc, 79, pp. 847-854Mittelbach, M., Diesel fuel derived from vegetable oils. VI: Specifications and quality control of biodiesel (1996) Bioresour. Technol, 56, pp. 7-11Standard test method for iodine value of drying oils and fatty acids Annual Book of ASTM Standards, pp. 277-279. , ASTM D1959-85, Vol. 06.03, ASTM International, West Conshohocken, PA, 1985Standard test method for iodine value of drying oils and their derivatives (1986) Annual Book of ASTM Standards, pp. 210-212. , ASTM D1541-86, Vol. 06.03, ASTM International, West Conshohocken, PABouaid, A., Martinez, M., Aracil, J., Production of biodiesel from bioethanol and brassica carinata oil: Oxidation stability study (2009) Bioresour. Technol, 100, pp. 2234-2239Knothe, G., Dependence of biodiesel fuel properties on the structure of fatty acid alkyl esters (2005) Fuel Process. Technol, 86, pp. 1059-1070Knothe, G., Some aspects of biodiesel oxidative stability (2007) Fuel Process. Technol, 88, pp. 669-677Xin, J., Imahara, H., Saka, S., Oxidation Stability of Biodiesel Fuel as Pre-pared by Supercritical Methanol (2008) Fuel, 87, pp. 1807-1813Bouaid, A., Martinez, M., Aracil, J., Long storage stability of biodiesel from vegetable and used frying oils (2007) Fuel, 86, pp. 2596-2602Naz, S., Sheikh, H., Saddiqi, R., Sayeed, S.A., Oxidative stability of olive, corn and soybean oil under different condition (2004) Food Chem., 88, pp. 253-259Kodali, D.R., High performance ester lubricants from natural oils (2002) Ind. Lubr. Tribol, 54, pp. 165-170Imahara, H., Minami, E., Saka, S., Thermodynamic study on cloud point of biodiesel with its fatty acid composition (2006) Fuel, 85, pp. 1666-1670AOCS official method cd 1-25. iodine value of fats and oils wijs method (1998) Official Methods and Recommended Practices of the American Oils Chemists' Society, , AOCS, 5th ed., D. Firestone, Ed., AOCS, Champaign, ILFat and Oil Derivatives-Fatty Acid Methyl Esters (FAME)Determination of Iodine Value, , EN 14111, 2003, " European Committee for Standardization, BerlinMargosches, V.B.M., Hinner, W., Friedmann, L., Über eine Schnellmethode zur Bestimmung der Jodzahl fetter Öle mit Jod und Alkohol (1924) Angew. Chem., 37, pp. 334-337(1996) An Encyclopedia of Chemical, Drugs and Biological, pp. 860-861. , The Merck Index, 12th ed., S. Budavari, Ed., Merck Reserch Laboratories, Whitehouse Station, NJEckschlager, K., (1972) Errors, Measurement and Results in Chemical Analysis, pp. 109-120. , Van Nostrand Reinhold Company, London