E Enhanced Oil Recovery (EOR) is one of the methods employed to optimize oil production. At this time, the longer the petroleum production, the lower the production. So it requires a way to increase petroleum production to the maximum. One of the ways to achieve maximum production is to use the Enhanced Oil Recovery method. Surfactant injection functions to lower the interface tension so that the oil can move towards the production well and can go to the surface. In small amounts of surfactant added to the formation water, it is useful to reduce the interface tension and mechanical energy for foam formation. This study aims to evaluate the influence of Methyl Ester Sulfonate (MES) surfactant concentration, derived from palm oil, on improving oil recovery. The research method utilized is laboratory experimentation using crude oil with an API gravity of 41° sourced from a specific oil field. Synthetic Berea core samples were employed in the experiments. Tests were conducted using MES surfactant at varying salinity levels, followed by an analysis of its performance under these conditions. Salinity was observed to significantly influence the effectiveness of the MES surfactant. The experimental methodology involved laboratory studies using palm oil-based MES surfactant with a concentration of 1.25% in brine solutions with salinities of 5,000, 7,000, 10,000, and 12,000 ppm at a temperature of 60°C. The aqueous stability tests demonstrated that all surfactant solutions were stable and homogeneous. In the phase behavior tests, the MES surfactant formed the optimal middle-phase emulsion at a salinity of 5,000 ppm, achieving a phase volume of 4.25% and an interfacial tension (IFT) of 2.68E-01 dyne/cm. Additionally, imbibition tests indicated that the MES surfactant achieved a recovery factor of 84.26%. These results demonstrate that the addition of palm oil-based MES surfactant contributes significantly to enhancing the recovery factor in oil recovery processes.