Esters are valuable compounds in fine organic synthesis and industry. The significant growth in the demand for esters requires the development of scalable production methods. Heterogeneous CaO-based catalysts for the production of esters by transesterification are promising catalytic systems for the production of these desired compounds. In this work, the application of calcium carbide slag, a byproduct of acetylene production, was investigated. The catalyst was obtained by calcination of calcium carbide slag at 600 °C (CS 600) and characterized by XRD and FTIR analysis. The transesterification reactions were carried out with primary alcohols, producing fatty acid alkyl esters in 51-99% yields, depending on the alcohols' nature and catalyst amount (1-10 wt %). The CS 600 catalyst demonstrated efficiency in the transesterification of low-molecular-weight esters, medium-chain triglycerides (C 9-C 12), and lactones, resulting in the corresponding methyl esters in 66-99% yields in the presence of low catalyst amounts of 1-5 wt %.