Catalytic biodiesel production from sunflower oil and ethanol using K2CO3/γ-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% γ-Al2O3 hollow cylinder catalyst was used at 80 °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. The authors are grateful to Program of the Madrid Community AlcCones, S2013/MAE-2985, Spain and to the Brazilian agencies: Carlos Chagas Filho Research Foundation of the Rio de Janeiro State (FAPERJ) (Process no. E- 26/210.508/2014 ) and The National Council for Scientific and Technological Development (CNPq) (process no. 165577/2013-14 and 311942/2015-6 ) for the financial support.