Microbial-enhanced oil recovery is one of the most important tertiary recovery processes, which rise up the oil recovery ≈3%. The aim of this work was evaluate the surface activity of mannosylerythritol lipid under extreme conditions (pH, temperature and ionic strength) - one at a time and their interactions – which represents similar environmental of wells. Mannosylerythritol lipid was produced at bioreactor scale (7.5L) using cassava wastewater as substrate. Then, it was collected, centrifuged and purified by ultrafiltration. The pH (2 to 12), temperature (during 1h: 79, 100 and 121ºC) and ionic strength (2.5, 5, 10 and 20g/L of synthesized brine) were first investigated once at a time. Surface tension (ST) and its critical micelle dilutions 10x (CMD-1) and 100x (CMD-2) were measured. Thereafter, the Central Composite Design (CCD) experiments evaluated the interactions of conditions. The ionic strength did not significantly affect the surface activity property of mannosylerythritol lipid, since were observed low surface tension values even under high ionic strength (20g/L), ≈26mN/m. Mannosylerythritol lipid showed good surface activity under wide pH range (2-10). It also presented relative correlation with temperature (ST did not show changes, but CMD-1 was inversely proportional). Regarding to CCD of mannosylerythritol lipid, the ANOVA of ST, CMD-1 and CMD-2 indicated that all parameters were statistically differents. The CCD analysis of mannosylerythritol lipid was based only on CMD-2 (highest r2 0.84). Thus was generated the following equation: [CMD-2 for mannosylerythritol lipid] = 47.76 + 5.15 x (temperature) + 9.16 x (pH)2 + 5.34 x (ionic strength)2. The most predicted values (CMD-2) of mannosylerythritol lipid were similar to experimental. The validation showed that experimental values (52.35, 43.83, 48.02mN/m) were similar to predicted values (47.76mN/m). Mannosylerythritol lipid showed surface activity under extreme condition has good potential to be used for oil recovering.