Liquid-liquid equilibria in binary mixtures Of Substituted benzenes (toluene, ethylbenzene, propylbenzene, xylene isomers, trimethylbenzene isomers, aniline, nitrobenzene, phenol, and benzaldehyde) with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf(2)N]), have been measured using a mass-volume technique over a temperature range from about (293 to 373) K. Trends in both the polarity and molecular size of the Solute with the immiscibility gap were discovered for the alkyl-substituted benzenes. In general, as the polarity increased and the molecular size decreased, the immiscibility gap became smaller. The nonalkyl-substituted benzenes containing functional groups (-NH(2), -NO(2), -OH, and -CHO) were completely soluble in [emim][Tf(2)N] over the composition and temperature range Studied. The excess molar volumes for the ionic liquid-rich side solutions range front (-1 to -5) cm(3.)mol(-1), and the magnitudes are somewhat larger than those of ordinary liquid Solutions. Observed LLE are well correlated by use Of the nonrandom two liquid (NRTL) Solution model.