The research has been done about study effect variations of KOH catalyst concentration of biodiesel parameters from ketapang seed oil (Terminalia catappa Linn). The purpose of the research is to determine the optimum KOH concentration of biodiesel ketapang seed oil at 1; 1.5; 2; 2.5; and 3% to measure the parameters of biodiesel by the methond of ASTM (American Society for Testing Materials). T…