This review discusses the transesterification of vegetable oils, focusing on the production and applications of fatty acid methyl esters (FAMEs). The process involves the reaction of vegetable oils with methanol in the presence of various catalysts, including acids, bases, enzymes, and non-ionic bases such as guanidines. The review highlights the importance of catalyst selection, reaction conditions, and the use of heterogeneous catalysts to improve efficiency and reduce leaching. Guanidines are particularly noted for their ability to be heterogenized on organic polymers, although leaching remains a challenge. New strategies for more stable guanidine-based catalysts are proposed. The review also covers the industrial applications of FAMEs, including their use as biodiesel and in the production of various chemical products. The study emphasizes the advantages of using non-ionic bases, such as guanidines, in transesterification processes due to their high catalytic activity and potential for heterogeneous catalysis. The review concludes with a discussion on the environmental and industrial implications of using heterogeneous catalysts in transesterification processes.This review discusses the transesterification of vegetable oils, focusing on the production and applications of fatty acid methyl esters (FAMEs). The process involves the reaction of vegetable oils with methanol in the presence of various catalysts, including acids, bases, enzymes, and non-ionic bases such as guanidines. The review highlights the importance of catalyst selection, reaction conditions, and the use of heterogeneous catalysts to improve efficiency and reduce leaching. Guanidines are particularly noted for their ability to be heterogenized on organic polymers, although leaching remains a challenge. New strategies for more stable guanidine-based catalysts are proposed. The review also covers the industrial applications of FAMEs, including their use as biodiesel and in the production of various chemical products. The study emphasizes the advantages of using non-ionic bases, such as guanidines, in transesterification processes due to their high catalytic activity and potential for heterogeneous catalysis. The review concludes with a discussion on the environmental and industrial implications of using heterogeneous catalysts in transesterification processes.