Ion-exchange resins based on styrene (S) and divinylbenzene (DVB) were prepared by aqueous suspension polymerization using toluene and n-heptane as diluents for the monomers. The different morphological structures were characterized by surface area, pore volume, optical appearance and surface morphology. Sulfonic catalysts were prepared from these resins in the presence of solvents with solvating and non-solvating characteristics. These catalysts were characterized and their activities were evaluated in vegetable oil transesterification with methanol and compared with the performance of a commercial sulfonic resin. The synthesized resin presented better results than the commercial one representing a convenient route for biodiesel production. (c) 2008 Elsevier B.V. All rights reserved.