This study was conducted to investigate the active role of sulfated zirconia catalyst in the transesterification of palm (Elaeis guineensis) and sea mango (Cerbera odollam) oils. Initially, the sulfated zirconia catalysts were prepared and optimized under various preparation conditions - calcination temperature, calcination period and ratio of Zr-species/support - and then characterized for its physical and chemical properties. The performance of the sulfated zirconia catalysts was tested in the transesterification of palm oil and sea mango oil. The optimized sulfated zirconia catalyst was also tested for its reusability and regenerability. From this study, it was found that the best (optimum) sulfated zirconia catalyst was prepared using calcination temperature of 400 degrees C, calcination period of 2.5 h and ratio of Zr-species/support of 2 g g(-1). It was also found that the prepared sulfated zirconia catalyst contains acid sites which become the key factor in the transesterification process. The optimized sulfated zirconia catalyst was shown to be able to produce high yield of fatty acid methyl esters (> 80%) even with oil that has high free fatty acids content i.e. sea mango oil. The reusability and regenerability study showed that the optimized sulfated zirconia can be regenerated and reused repeatedly with an average of 5% loss in activity after each run. (C) 2012 Elsevier Ltd. All rights reserved.