Abstract Many countries produced biodiesel from crude vegetable oil. However, current vegetable oil feedstock to produce biodiesel slow the growth of biodiesel blend implementation due to the high cost of feedstock production. As a result, waste cooking oil (WCO) is claimed to be economic and readily available without cultivation and highly potential feedstock for high yield biodiesel. In this study, Fe-exchanged montmorillonite K10 (Fe-MMT K10) was employed as a catalyst in converting WCO to biodiesel. In comparison, Fe-MMT K10 was able to produce 95.26% biodiesel, which is higher than biodiesel produced using unmodified MMT K10 as catalyst and reaction without catalyst (38.39% and 29.50%, respectively). The full process of biodiesel production was carried out by response surface methodology (RSM) in conjunction with the central composite design (CCD) for statistically optimization and modelling. From the ANOVA, it was found that the production of biodiesel achieved an optimum level of 92.74% biodiesel at 134.07 °C, under a specific optimized condition of 6.32 h reaction time, 4.68 wt% of catalyst and 11.77:1 methanol to oil ratio.