NOVELTY - Preparing a catalyst (C') involves: introducing a base precipitant, a neutral precipitant, and an acid precipitant to a solution comprising a first metal ion and a second metal ion to form a precipitate; and calcining the precipitate to provide the catalyst.    USE - For preparing a catalyst (preferably heterogeneous catalyst), useful for producing biofuel (claimed).    ADVANTAGE - The method is suitable for producing catalysts, such as heterogeneous catalysts comprising calcium compound and lanthanum compound, particularly suitable for production of biodiesel through transesterification reactions of raw materials in presence of alcohol, where the raw materials comprise those having relatively high water and free fatty acid contents, such as crude oils; where the prior art calcium-containing catalysts showed much lower activities than NaOH, a conventional homogeneous catalyst, such that transesterification reactions using these catalysts usually are conducted at elevated temperatures and pressures, and it is desirable to maximize surface concentration of active catalytic sites. The required high-loading of active components, however, cannot be easily obtained using impregnation method; can be obtained using physical mixing, but has a drawback of low crystallinity of the catalysts, which has negative effect on the catalytic activity; and high-loading catalyst generally results in low specific surface area, and thus low surface concentration of catalytic sites for transesterification. The method for the production of catalysts is developed, while considering the effects of multiple precipitants in the preparation process on structure and performance of Ca-based solid catalysts and their performance in oil transesterification with methanol; where from the prior art it was found that single precipitant usually cannot effectively precipitate all metal ions in a solution. The catalyst precipitation process utilizes ammonia solution (as base precipitant), carbon dioxide (as acid precipitant), and ethanol (as neutral precipitant). The novel catalysts are solid base catalysts, comprising a mixture of segregated lanthanum and calcium oxide crystals, having specific surface area of more than 10 m2/g, and further total basicity of 13.6 mmol/g; and have high activities in catalyzing oil transesterification reactions and can convert non-refined oils into fatty acid methyl esters (FAME). Thus multi-step precipitation results in CaO-La2O3 based catalyst with relatively high base strength, basicity, specific surface area, and site concentration. Due to novel features of the catalysts, transesterification reactions using catalysts can utilize crude oils, waste cooking oil, and rendered animal fats, which are less expensive compared to food grade vegetable oils although they usually contain high content of free fatty acids (FFA) and water. Thus, using the catalysts can significantly reduce the cost of producing biodiesel.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) new heterogeneous catalyst (C1) comprising: calcium hydroxide and lanthanum hydroxide, where the catalyst has a specific surface area of more than 10 m2/g;    (2) new heterogeneous catalyst (C1a) comprising: calcium oxide and lanthanum oxide, where the catalyst has a specific surface area of more than 10 m2/g;    (3) new heterogeneous catalyst (C1b) comprising: a calcium compound and a lanthanum compound, where the catalyst has a specific surface area of more than 10 m2/g, and a total basicity of 13.6 mmol/g; and    (4) producing biofuel involving: contacting a feed material that comprises a glyceride with an alcohol in the presence of the catalyst (C1), (C1a) or (C1b) such that at least some of the glyceride in the feed material is converted into the corresponding alcoholic ester of the glyceride.