The liquid-liquid equilibria (LLE) data are presented for mixtures of alkane (C10/C12/C14) + octylbenzene + sulfolane at 323.15, 348.15 and 373.15 K. The addition of octylbenzene to sulfolane is found to increase the solubility of alkanes in the order of decane > dodecane > tetradecane. The tie line data were correlated with the well-known UNIQUAC and NRTL models. The calculated values based on the UNIQUAC model were found to be better than those based on the NRTL model. The values of selectivity and distribution coefficient were derived from the equilibrium data.