Calcium oxide (CaO) is one of the most commonly used heterogeneous base catalysts in the biodiesel synthesis process. The high CaCO3 content in the blood clam shell can be used as a catalyst in the synthesis of biodiesel using crude palm oil (CPO). Biodiesel production using a KOH/CaO catalyst derived from blood clam shell. KOH/CaO catalyst was synthesized using the sol-gel method by mixing…