To tackle the concerns of high energy consumption during desulfurization of heterocyclic sulfur compounds from diesel via adsorption, catalytic oxidation, hydrodesulfurization and other techniques used by petroleum refineries, adsorption using an ionic liquid (IL) based adsorbent has been identified as a promising alternative. In this study, a synthesized IL based adsorbent was applied to adsorb heterocyclic sulfur compounds, viz. thiophene and dibenzothiophene, from a model diesel. A maximum of 98.81% desulfurization efficiency has been achieved after 60 min at a fixed feed to adsorbent (15 wt % IL loaded) ratio of 1 : 0.075. The adsorbent with no IL fitted Henry’s model of adsorption isotherm whereas adsorbent with 5 and 20 wt % IL loading followed standard Type-IV isotherm and adsorbent with 10 and 15 wt % loading agreed well with standard Type-III isotherm. 5, 10, 15, and 20 wt % loaded IL adsorbents best fitted with Freundlich, Jovanovich, Langmuir and Harkins–Jura isotherm, respectively. From adsorption kinetics study, it is inferred that 5 wt % loaded adsorbent followed Elovich model, 10% as well as 15% loaded adsorbents agreed well with pseudo 2nd order kinetics and 20% loaded adsorbent followed pseudo 1st order kinetics.