Much attention has been drawn to “Biodiesel” as a renewable liquid fuel, but the production using alkali hydroxide resolving in the reactant is always accompanied by environmentally malign effluents. This problem is evitable by using calcium oxide as the solid base catalyst. The strong basic property under the reacting condition of including a trace amount of moisture enhanced the catalytic activity for the chemical reaction to produce biodiesel. For preparing the practical catalyst, calcium oxide was anchored onto silica. The composite powder can be formed into macro-porous pellet by controlling the densification, which may further enhance the catalytic effectiveness factor.