Methyl or ethyl esters of long chain fatty acids are called biodiesel. Biodiesel is synthesized by the alcoholysis of oils/fats. In this work, lipase from Thermomyces lanuginosus was precipitated over the clusters of Fe3O4 nanoparticles. This biocatalyst preparation was used for obtaining biodiesel from soybean oil. After optimization of both immobilization conditions and process parameters, complete conversion to biodiesel was obtained in 3 h and on lowering the enzyme amount, as little as 1.7 U of lipase gave 96% conversion in 7 h. The solvent free media with oil: ethanol (w/w) of 1: 4 and 40 degrees C with 2% (w/w) water along with 20% (w/w) silica (for facilitating acyl migration) were employed for reaching this high % of conversion. The biocatalyst design enables one to use a rather small amount of lipase. This should help in switching over to a biobased production of biodiesel. (C) 2016 Elsevier Ltd. All rights reserved.