Apart from calcium, the CaO catalyst obtained from the calcination of chicken manure also contains other basic elements i.e. potassium (7 wt%), magnesium (4 wt%) and Zinc (6 wt%). It has been reported in the literature [36] that the addition of K or Mg as a promoter in the CaO catalyst has enhanced the FAME yield during the transesterification reaction of soybean oil and ethanol, while the addition of Zn has insignificant effect. Therefore, the presence of K and Mg in the CaO catalyst obtained from the calcination of chicken manure can probably enhance the catalytic performance of the catalyst.