The requirements of solid heterogeneous catalyst are always needed for the synthesis of biodiesel. New environment friendly and cheaper alternatives of solid catalyst are always on demand. Activated charcoal may play a good role in this field and fulfill all criteria of requirement. In this article, we have reported synthesis of cheap charcoal catalyst from wood of poplar tree and sesame. Functionalized activated charcoal has been used as a catalyst for esterification of decanoic acid. The studies show that the optimal parameters for the conversion of decanoic acid into its ester are found to be 333K temperature and 7 wt% catalyst amount using a batch reactor. The significant fuel properties of synthesized methyl decanoate are found to be as per ASTM standards. Analysis of charcoal catalyst and its reusability is also determined in this study.