The effect of reaction time on the conversion of palm oil to FAME was investigated. Reaction time is one of the key parameters during the transesterification carried out in glass reactor. Figure 5 shows a gradual increase in the yield with time from 1 to 5h with a catalyst amount of 20 wt.% relative to oil and a methanol/oil molar ratio of 9:1. The maximum yield of 92.92 and 94.49% were obtained in 4h at 60°C for duck and chicken eggshell waste, respectively. In the initial stages of the transestherification reaction, production of methyl esters was rapid, and the rate diminished and finally reached equilibrium [15,18] in about 4h. This can be explained by that transesterification reaction between oil and alcohol is reversible, when the reaction time is long enough [19].