In present paper experimental data on extractive desulfurization of liquid fuel using trihexyl tetradecyl phosphonium bis (2,4,4-trimethyl pentyl) phosphinate has been presented. The FTIR, 1H NMR, 13C NMR, 31P NMR, and ESR have been discussed for the molecular confirmation of synthesized phosphonium based ionic liquid. Further, conductivity, solubility, and viscosity analyses of phosphonium ionic liquids were carried out. The effects of reaction time, reaction temperature, sulfur compounds, ultrasonication, and recycling of ionic liquid without regeneration on removal of dibenzothiophene from liquid fuel were also investigated. In extractive desulfurization process, the removal of dibenzothiophene in n-dodecane was 79.5% for mass ratio of 1:1 in 30 min at 30 C under the mild reaction conditions. Phosphonium ionic liquids could be reused five times without a significant decrease in activity. Also, the desulfurization of real fuels, multistage extraction was examined. The data and results provided in present paper explore the significant insights of phosphonium based ionic liquids as novel extractant for extractive desulfurization of liquid fuels. © 2014 Published by Elsevier B.V.