The production of biodiesel from transesterification of palm oil with methanol was studied by using CaO-ZnO prepared by incipient-wetness impregnation (IWI) and co-precipitation (CP) methods as a heterogeneous base catalyst. The optimum conditions—15:1 molar ratio of methanol to oil, a catalyst amount of 6 wt.%, reaction temperature of 60 °C, and reaction time of 8 h—were suggested to obtain a biodiesel yield of 79.62 % and 78.88 % for the catalyst prepared by IWI and CP techniques (Ca:Zn atomic ratio of 1:3 and calcination temperature of 800 °C), respectively. During the three cycles of the catalyst’s durability observation, the durability of the CaO-ZnO catalyst prepared by IWI technique was much better than that of catalyst prepared by CP technique because the higher amounts of CaO remaining on the IWI catalyst attributed to less CaO leaching during the reaction, evidenced by XRD results of the spent catalysts.