In this study, optimization of biodiesel production from castor oil using full factorial design was investigated. The biodiesel production was carried out in a batch laboratory scale reactor by alkaline-catalyzed transesterification process. Experimental design was used in the evaluation of process variables. Effects of temperature, methanol/oil molar ratio and catalyst concentration were optimized according to the 2(3) full factorial central composite design (CCD). For determining the influence of purification methods on biodiesel yield, different purification methods were applied to the product after transesterification reaction. Second-order model was obtained to predict biodiesel yield as a function of these variables. According to the experimental results this process gave an average yield of biodiesel more than 90%. (c) 2013 Elsevier B.V. All rights reserved.