The influence of synthesized ionic liquid 1-hexyl-3-methylimidazolium chloride adsorption on equilibrium interfacial tension of toluene-water was studied within concentration range of (1.00 . 10(-4) to 6.00 . 10(-1)) mol . dm(-3) and temperature range of (293.2 to 313.2) K. Very similar to conventional surfactants, the interfacial tension was decreased with both of these parameters. Meanwhile, the CMC values showed a minimum value within the temperature range studied. The Frumkin adsorption isotherm that accounts for the non-ideal adsorption at the interface showed adequately well for modeling the experimental results. Accordingly quantities like interface excess concentration, adsorption tendency and interaction parameter between adsorbed molecules were obtained at different temperatures. Entropy and energy changes associated with adsorption were also obtained from the temperature dependency of interfacial tension. The adsorption tendency and efficiency increased with temperature, and the maximum interface excess concentration and electrostatic repulsion were achieved at about T = 303.2 K. (c) 2013 Elsevier Ltd. All rights reserved.