T The decline of conventional oil reserves in indonesia has prompted the need for more efficient and sustainable enhanced oil recovery (eor) technologies. this study investigates the effect of pineapple peel solution as a co-surfactant in a surfactant system based on sodium lignosulfonate (sls) derived from pine wood,focusing on emulsion quality and oil recovery effectiveness. the formulation was tested at various surfactant concentration 1% and brine salinities (5000 ppm, 8000 ppm, 10000 ppm, 12000 ppm). the experiments included phase behavior tests, compatibility assessments, interfacial tension (ift) measurements, core floodinganalysis, and micromodel visualization. results from a sample containing 1% sls pine wood surfactant with 8000 ppm salinity demonstrated that adding 1% pineapple peel solution enhanced emulsion stability and significantly reduced ift to 4.19 mn/m. these findings propose an environmentally friendly formulation approach applicable for optimizing chemical eor injection, with a recovery factor of 4.65% from 2.15 cm³ of original oil in place, as observed in the core flooding test.