In this work, the extractive and oxidative deep desulfurizations Of model fuel oils using a low-viscosity ionic liquid, i.e., 1-ethyl-3-methylimidazolium dicyanamide ([C(2)mim][N(CN)(2)]), are investigated. [C(2)mim][N(CN)(2)] is capable of effectively extracting thiophene (TS) and dibenzothiophene (DBT) from oils. The sulfur content in the raffinate phases is only similar to 10 ppm after a few extraction steps. A short extraction equilibrium time of <5 min is observed The extraction operation is insensitive to temperature, and it can be effectively performed at or around room temperature. Unexpectedly, the oxidative removal of DBT by such a dicyanarnide-based ionic liquid is not effective and is not as good as the corresponding extraction operation. Such an undesirable oxidative desulfurization is understood at a molecular level from ab initio calculations, and it may be ascribed to the strong intermolecular interaction between CH3COOH or CH3COOOH and [C(2)mim][N(CN)(2)] Phase. Therefore, such a dicyanamide-based ionic liquid is efficient for direct extractive desulfurization, while it is less efficient for oxidative desulfurization.