beta-Cyclodextrin functionalized reduced graphene oxide hybrid nanosheets (beta-CD-RGO) were successfully prepared by using L-ascorbic acid (L-AA) as the reducing agent under a mild condition and used as enhanced material for sensitivity determination of diethylstilbestrol (DES). In 0.1 M PBS (pH 7.0), the redox peak currents of DES increased significantly on beta-CD-RGO modified glassy carbon electrode (beta-CD-RGO/GCE), suggesting that the composite film not only shows excellent electronic properties of RGO sheets but also exhibits high supramolecular recognition capability of beta-CD. The experimental conditions were optimized and the kinetic parameters were investigated. Under the optimal conditions, the reduction peak current of DES increased linearly with increasing the concentration in the range from 0.01 to 13 mu M with the detection limit of 4 nM (S/N = 3). The developed electrochemical sensor exhibited high selectivity, good stability and reproducibility, and also successfully determined DES in milk samples with satisfactory results. (C) 2012 Elsevier Ltd. All rights reserved.