Iron magnetic nanoparticles (Fe3O4) were evaluated as adsorption preparative heterofunctional support for the immobilization of lipase B from Candida antarctica (CALB). Heterogeneous magnetic catalysts are easy to recover by the magnetic field, which may optimize operational cost and enhance the purity of the products. The nanoparticles were produced by the co-precipitation method. Modifications were carried out on the nanoparticles' surfaces with aminopropyltriethoxysilane (APTS). The adsorption was evaluated for 3.0 mg protein/g of support in the presence of 5mM sodium phosphate buffer, pH 7.0, at 25 °C and 0.5h of immobilization. In a solvent-free medium, under 37 °C, the biocatalyst prepared has shown activity of 2.2 U/g for the esterification of oleic acid after 0.5h, 37 kHz, and 300 W. The results obtained with CALB adsorbed onto magnetic iron nanoparticles were compared with those of lipase B from Candida antartica adsorbed onto acrylic resin (Novozym® 435). In this regard, under the same reactional conditions, Novozym® 435 has presented activity of 2.9 U/g.