Catalytic biodiesel production from sunflower oil and ethanol using K2CO3/gamma-Al2O3 in different configurations has been studied. To prepare the catalysts, boehmite was extruded with the aid of a binder and different percentages of K2CO3 active phase (15-45%) impregnated on the supports for comparative purposes. The transesterification reactions were carried out during 4 h using 5 wt% of the catalyst and the effects of oil: alcohol molar ratio and temperature were investigated to improve biodiesel formation. The best result (99.3% conversion) was obtained when 35% K2CO3/65% gamma-Al2O3 hollow cylinder catalyst was used at 80 degrees C and 1:12 oil: ethanol molar ratio, showing their potential as promising alternative to conventional homogeneous catalytic systems used for biodiesel production at industrial scale.