KF-impregnated nanoparticles of-gamma-Al2O3 were calcinated and used as heterogeneous catalysts for the transesterification of vegetable oil with methanol for the synthesis of biodiesel (fatty acid methyl esters, FAME). The ratio of KF to nano-gamma-Al2O3, calcination temperature, molar ratio of methanol/oil, transesterification reaction temperature and time, and the concentration of the catalyst were used as the parameters of the Study. A methyl ester yield of 97.7 +/- 2.14% was obtained under the catalyst preparation and transesterification conditions of KF loading of 15 wt%, calcination temperature of 773 K, 8 h of reaction time at 338 K, and using 3 wt% catalysts and molar ratio of methanol/oil of 15:1. This relatively high conversion of vegetable oil to biodiesel is considered to be associated with the achieved relatively high basicity of the Catalyst Surface (1.68 mmol/g) and the high surface to Volume ratio of the nanoparticles of gamma-Al2O3. (C) 2009 Elsevier B.V. All rights reserved.