ABSTRACT Calcium oxide catalysts prepared from golden apple cherry snail shell (Pomacea canaliculata) via two steps - deproteination and calcination - were compared: the structure was characterized by XRD and XRF and morphology by SEM. In addition, the effects of reaction time, catalyst loading amount, methanol:oil molar ratio and reaction temperature on the biodiesel yield were measured. The optimum conditions for biodiesel production, 0.8 wt% catalyst loading, 12:1 methanol:oil molar ratio, 65 OC reaction and 6 h reaction time, gave a biodiesel up to 95.2%. Moreover, the catalyst demonstrated high stability, permitting reuse for up to four cycles with biodiesel yield falling by only 4%.