The alkaline-catalyzed (KOH) ethanolysis of rapeseed oil with the help of a mechanical disperser was researched in this study. The effects of chosen reaction conditions (independent variables: the reaction temperature and time, the amount of catalyst, the molar ratio ethanol to oil and the rotation frequency of the disperser) on the ethanolysis process and ways for the improvement of the transesterification and separation process were studied. The transesterification of oil, the separation of the ester phase from the glycerol phase and qualitative properties of the ester phase were monitored by many dependent variables (e.g. the yield of the ester phase, the weight concentration of glycerides, the content of potassium ions, etc.). The measured data was analyzed by multi-linear regression with the help of many statistical tests (significance of parameters, exclusion of outliers, etc.). The created mathematical models describing the relations between the independent and dependent variables were verified by several independent experiments. (C) 2009 Elsevier Ltd. All rights reserved