Jatropha curcas contains extractable renewable non-edible oil which can be converted into surfactant suitable for oil recovery due to its hydrophilic property. Chemically, it contains high fatty acid components comprised primarily of oleic acid (44.7) and linoleic acid (32.8). In this study, a surfactant based on Jatropha oil was developed and tested against the interface tension reduction in the presence of alkaline, co-solvent and brine. Jatropha fatty acid was extracted via saponification process and neutralized with sodium hydroxide yielding sodium fatty acid. The performance of the synthesized surfactant was studied by measuring the interfacial tension (IFT) between the surfactant solution and crude oil, and its phase behaviour at reservoir temperature. Phase behavior is dependent upon the surfactant, alkaline and brine concentration, which are expressed as viscosity of the microemulsion. In order to mobilize residual oil trapped by capillary forces in oil reservoirs, many enhanced oil recovery (EOR) methods rely on reducing the oil-water IFT to extremely low values by using lowest surfactant concentration. Dulang crude oil used have high contain of wax and low acid value react with surfactant which contains fatty acid and reacts with the alkaline solution to produce in situ surfactant (ionized acid) which be able to lowers the oil-water IFT. The ionized acid is surface active and has a tendency to partition into the aqueous phase where it may form soap with sodium ions present in the surfactant and aqueous phase at a high ionic strength. The soap has a trend to partition into the oil phase. The removal of the ionic acids from the interface can cause low dynamic IFT. The result of this work indicates that the lowest IFT of surfactant concentration are distinctive for the different alkaline concentration. Significantly, the increase of surfactant concentration amplified the microemulsions. This enhanced the viscosity of the aggregated phase. Furthermore, makes the process economical for the best oil recovery. © 2011 IEEE.