The solubilities of benzene in micellar solutions of cetyltrimethylammonium bromide (CTAB)/D2O and decyltrimethylammonium bromide (DTAB)/D2O, and in D2O have been determined by H-1 NMR spectroscopy, The average solubility of benzene in 0.15 M CTAB/D2O was found to be 3.35 +/- 0.05% (wt/wt) (benzene/0.15 M CTAB/D2O), 1.18 +/- 0.09% (wt/wt) (benzene/0.15 M DTAB/D2O) in 0.15 M DTAB/D2O, and 0.074 +/- 0.004% (wt/wt) (benzene/D2O) in D2O, Values of Delta G = -5.0 kcal/mol and -4.8 kcal/mol were determined for the free energy of transfer of benzene from D2O to micelle for 0.15 M CTAB/D2O and 0.15 M DTAB/D2O micellar solutions,respectively.