BACKGROUNDThis study investigation was carried out to obtain better quality biodiesel from robust biomass, Scenedesmus sp. through in situ transesterification with acid catalysis. RESULTSThe overall biodiesel yield from this process was estimated as c. 85 (% w/w) based on the theoretically maximum production yield of 69.36 (% w/w) from total lipids in the biomass, compared with 64 (%, w/w) from a conventional Taguchi extraction process. The quality of this biodiesel was analyzed by FT-IR and H-1-NMR, showing very similar characteristics to other algal biodiesel. Fatty acid methyl ester (FAME) conversion yield was obtained as 96.5%, which was higher than those from conventional transesterification processes. The result of thermogravimetric analysis (TGA) was 99.99% volatile yield and 0.01% ash, which was also better than those from other algal biodiesel. This biodiesel showed 37.95 MJ kg(-1) of higher calorific value (HCV) and 23.92 MJ kg(-1) of lower calorific value (LHV), respectively. CONCLUSIONThe results proved that the biodiesel from Scenedesmus sp. through a simple and economic process had high quality and also fulfilled most of the requirements of ASTM D6751 or EN 14214 for biodiesel. (c) 2014 Society of Chemical Industry