One-pot synthesized Ti-SBA-15 mesoporous materials with various Ti loadings of 0.808-6.78 mol% were applied as heterogeneous solid acid catalysts for simultaneous esterification and transesterification of vegetable oils with methanol into high-quality biodiesel fuel (BDF) at 200 degrees C under autogeneous pressure. According to the diffuse-reflectance (DR) UV-vis spectra, diffuse-reflectance infrared Fourier transform (DRIFT) spectra and pulsed ammonia (NH3) chemisorption studies combined with other conventional characterizations, the catalytically active site for high-quality BDF synthesis was mostly related to the tetrahedral Ti4+ species with weak Lewis acid character, which differential heat of NH3 adsorption was lower than 90 kJ mol(-1). Due to that the tetrahedral Ti4+ species were accessible on largely mesoporous framework, the Ti-SBA-15 catalyst gave much higher activity in transesterification of crude Jatropha oil (CJO) with methanol than microporous titanosilicate of TS-1 and commercial TiO2 nanocrystallites. Among them, the 3Ti-SBA-15 catalyst with a Ti loading of 2.46 mol% showed a highest fatty acid methyl ester (FAME) content of 90 mass% at 200 C for 3 h using a methanol-to-oil molar ratio of 27. When the reaction period and methanol-to-oil molar ratio were increased to 3-6 h and 108, respectively, a great variety of edible and non-edible vegetable oils with various acid values (0.06-190 mg KOH including refined soybean oil (RSO), refined rapeseed oil (RRO), waste cooking oil (WCO), crude palm oil (CPO), CJO and palm fatty acid distillates (PFAD), was directly transformed into high-quality BDFs, which met with a European standard (EN 14214:2009), over 3Ti-SBA-15 catalyst at 200 degrees C. The used 3Ti-SBA-15 catalyst was easily regenerated by calcination and its high activity was maintained. Most importantly, the 3TiSBA-15 catalysts could resist 5 wt% of water or 30 wt% of free fatty acid (FFA), which tolerance levels were several ten times better than those of homogeneous and heterogeneous catalysts in the current BDF production technology. (C) 2013 Elsevier B.V. All rights reserved.