Biodiesel is an alternative to fossil fuels. It is produced by transesterification of triglycerides with short-chain alcohols in the presence of a catalyst. Sources of triglycerides include vegetable oils and animal fats. Among alkali metal oxide catalysts, calcium oxide (CaO) is widely used in the transesterification reaction. CaO is strongly alkaline and is cheap and environmentally friendly. It has low solubility in methanol. CaO can be sourced from natural limestone deposits. In this study, a solid CaO catalyst was obtained from Lintau Buo limestone and calcined at 900°C for 5 h. The results showed that this catalyst had a significant effect on biodiesel production.