The field of separation using hydrotropy has been studied. Solvent extraction and extractivedistillation with aqueous solutions of hydrotropes are the novel separation techniquessuitable for separation of close boiling mixtures. The present work is concerned with the separationof styrene-ethyl benzene mixture using hydrotropic solutions of urea, nicotinamide and sodiumbenzoate. The influence of a wide range of hydrotrope concentrations (0 to 3.0 mol/L) anddifferent system temperatures (303 to 333 K) on the separation of styrene and ethyl benzenemixture was studied. The percentage extraction of styrene from the styrene-ethyl benzene mixtureincreases with an increase in hydrotrope concentration and also with system temperature. AMinimum Hydrotrope Concentration (MHC) was found essential to initiate significant extractionof styrene from the styrene-ethyl benzene mixture. The maximum enhancement factor, which isthe ratio of the value in the presence and absence of a hydrotrope was determined. The Setschenowconstant, Ks, a measure of the effectiveness of a hydrotrope, was determined for eachcase.