Modified MgO superbasicity with CaO as nanostructure were prepared by hydration-dehydration method and used as heterogeneous catalyst for the synthesis of biodiesel (FAME) via the transesterification of sunflower oil with methanol. The synthesis of biodiesel was characterized by proton nuclear magnetic resonance (1H-NMR) and attenuated total reflectance (ATR). The catalyst was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA-DTG) and nitrogen gas adsorption (NA). The basicity of the prepared catalyst samples was also studied by back titration method. The optimal produced biodiesel was 97% at 25% molar ratio which carried out at atmospheric pressure, reaction time of 3 h, a reaction temperature of 65°C, a catalyst amount of 5 wt% and methanol:oil molar ratio of 9:1. The percentage conversion of biodiesel was determined by 1H-NMR. The modified nanostructure MgO with CaO showed tremendous potential in large-scale biodiesel from sunflower oil.