The reductions of sulfur content in gasoline and diesel fuel are great environmental concern to reduce the motor vehicle emissions. Oxidative desulfurization in acetonitrile biphasic system, proposed in recent years, can oxidize the unreactive sulfur compounds in the hydrodesulfurization. In this work, therefore, liquid-liquid equilibria (LLE) for acetonitrile+n-octane and+n-decane systems were measured with the tie-line measurement. The partition coefficients of benzothyophene, a major sulfur-containing compound in gasoline, and benzothyophene 1,1-dioxide, a major product of benzothyophene oxidative desulfurization reaction, for acetonitrile+n-octane system were also measured. Furthermore, the LLE was calculated with ASOG activity coefficient model to see the applicability of the model. 2004 Elsevier B.V. All rights reserved.