The optimization and transesterification of soybean oil with methanol in the presence of sodium hydroxide as a catalyst was investigated. A low-temperature transesterification process was selected to make the transesterification process more energy efficient. To further improve the production of biodiesel, the experimental design was carried out with the Box-Behnken method. The results were analysed using the response surface methodology. A model was developed to correlate the performance of biodiesel with the parameters of the process, such as the molar ratio, the concentration of the catalyst and the reaction time. The influence of the reaction variables, including; The molar ratio of oil (6: 1–12: 1), temperature (50° C) and catalyst concentration (1–2% by weight) and residence time (30–60 minutes) on the transesterification reaction of the methyl ester of Fatty acid (FAME) were studied. A biodiesel yield of 80.86% with the molar ratio (8:1) was reached using NaOH as catalyst (1.8) in 34 minutes at a temperature of 50° C. It was observed that the catalyst concentration, the reaction time and the molar ratio had a significant effect on the yield of soybean biodiesel.