Simultaneous determination of dihydroxybenzene isomers was investigated at a multi-wall carbon nanotubes (MWCNTs)/b-cyclodextrin composite modified carbon ionic liquid electrode in phosphate buffer solution (pH 7.0, 1/ 15 mol/L) in the presence of cationic surfactant cetylpyridinium bromide (CPB). With the great enhancement of surfactant CPB, the voltammetric responses of dihydroxybenzene isomers were more sensitive and selective. The oxidation peak potential of hydroquinone was about 0.024 V, catechol was about 0.140 V and resorcinol 0.520 V in differential pulse voltammetric (DPV) measurements, which indicated that the dihydroxybenzene isomers could be separated entirely. The electrode showed wide linear behaviors in the range of 1.2 Â 10 À7 -2.2 Â 10
À3, 7.0 Â 10 À7 -1.0 Â 10 À3 , 2.6 Â 10 À6 -9.0 Â 10 À4 mol/L for hydroquinone, catechol and resorcinol, respectively. And the detection limits of the three dihydroxybenzene isomers were 4.0 Â 10À7 mol/L, respectively. The proposed method could be applied to the determination of dihydroxybenzene isomers in artificial wastewater, and the recovery was from 97.4% to 104.2%.