Liquid-liquid equilibrium (LLE) data were measured for three binary systems containing sulfolane and branched cycloalkanes (methylcyclopentane, methylcyclohexane, and ethylcyclohexane) over the temperature range around 300-460 K using a circulation type equipment with an equilibrium view cell. The compositions of both branched cycloalkane-rich and sulfolane-rich phases were analyzed by on-line gas chromatography. The binary liquid-liquid equilibrium data were correlated with the NRTL model and UNIQUAC model using temperature-dependent parameters. The both models correlated with a good accuracy. (c) 2006 Elsevier B.V. All rights reserved.