Biodiesel is a promising renewable fuel which has a major weakness due to its instability against oxidative degradation. Its unsaturated fatty acid content is responsible for this drawback. Most of the biodiesel oxidation takes place during fuel blending and storage. This oxidation reaction may decrease the quality of biodiesel as a fuel, while the oxidation product could potentially harm the engine and decreases its performance. The oxidative degradation could be prevented by the addition of a phenolic antioxidant such as pyrogallol. Unfortunately, the solubility of phenolic compounds in biodiesel is relatively low. Several studies claimed that the solubility of phenolic and phenolic derivative compounds could be improved by the addition of alkyl group to its benzene ring. In the previous research, the addition of methyl linoleate to the benzene ring of pyrogallol using 1,1-diphenyl-2-picrylhydrazyl (DPPH) has been done to improve its solubility. The product was successfully synthesized; however, the yield was at a low concentration. In this research, the reaction condition was optimized by varying the mole ratio of pyrogallol to methyl linoleate and the amount of DPPH to produce a higher concentration of the new product. The result showed that the optimum mole ratio of pyrogallol to methyl linoleate is 1:200. The increase in DPPH amount increases the concentration of the product.