Liquid-liquid equilibrium (LLE) data were measured for four binary systems containing sulfolane and alkanes (pentane, hexane, heptane, and octane) over the temperature range around 300 K to the near upper critical solution temperature (UCST) using circulation-type equipment with an equilibrium view cell. The compositions of both alkane-rich and sulfolane-rich phases were analyzed by on-line gas chromatography. The binary liquid-liquid equilibrium data were correlated with the nonrandom two-liquid (NRTL) model using temperature-dependent parameters. The NRTL model correlated with good accuracy.