Chemical oil spill dispersants are toxic to the marine environment, spurring a search for environmentally friendly dispersant formulations. We have formulated an oil spill dispersant composed of two biocompatible surfactants, Tween 80 (T) and surface-active ionic liquid (SAIL), BMIM Lausar (1-butyl-3-methylimidazolium lauroyl sarcosinate). Various micellar, interfacial, and thermodynamic properties of Tween 80 and ionic liquid (T/IL) blends were studied. The T/IL blends were solubilized in simulated seawater, and their oil (light Arab crude oil) dispersion effectiveness was determined by the baffled flask test. A synergistic interaction was observed between T and IL, such that a blend is effective as an oil dispersant, but neither is effective on its own. The stability of crude oil droplets was maximized at a 40/60 (w/w) of T/IL. The dispersion effectiveness at this specific ratio was found to be 81.19%, with a dispersant to oil ratio (DOR) of 1:25 (volume). The size and size distribution of dispersed oil droplets at function of DOR were investigated using optical microscopy and particle size analyzer. The results showed that the sizes of oil droplets decreased with DOR. We conclude that T/IL blends have unique properties which make them viable alternatives for oil spill remediation. © 2021 Elsevier B.V.