Biodiesel is synthesized via the transesterification of lipid feedstocks with low molecular weight alcohols. Industrially, alkaline bases such as sodium and potassium hydroxides (NaOH-KOH) are used to catalyze the reaction. These catalysts require anhydrous conditions and feedstocks with low levels of free fatty acids (FFAs). Water in the reaction promotes the formation of FFAs, which can deactivate the catalyst and produce soap, an undesirable byproduct. Strong liquid acids are less sensitive to FFAs and can simultaneously conduct esterification and transesterification reactions. Solid catalysts based on Ni and Pt supported on mesoporous materials (SBA-15 and SBA-16) were tested in the synthesis of biodiesel by transesterification of a vegetable oil via acid catalysis. Textural and structural proprieties of the catalysts were characterized by N(2) physisorption (BET method), X-ray diffraction (XRD), and Transmission electron microscopy (TEM); the textural properties and XRD results showed the characteristic properties of mesoporous materials. The Cetane Index of the biodiesel obtained was tested and compared against the Cetane Index of conventional petroleum-based diesel. ASTM techniques used as comparison analysis for the synthetic biodiesel showed better properties than conventional diesel. (C) 2011 Elsevier B. V. All rights reserved.