A highly stable and effective electrochemiluminescence (ECL) sensing system of cadmium sulfide nanowires/reduced graphene oxide (CdS NWS/rGO) hybrid is presented for supersensitive detection of pentachlorophenol (PCP). CdS nanowire is for the first time exploited in ECL sensing. The rGO served as both ECL signal amplifier and immobilization platform, can perfectly enhance the ECL intensity and stability of the sensing system. With S2O82 as coreactant, the ECL signal can be significantly quenched by the addition of PCP. The established ECL sensing system presents a wider linear range from 1.0 x 10 (14) to 1.0 x 10 (8) M and a much low detection limit of 2 x 10 (15) M under the optimum test conditions (e.g., pH 7.0 and 100 mM S2O82). Furthermore, the ECL sensing system displays a good selectivity for PCP detection. The practicability of the ECL sensing system in real water sample shows that this system could be promisingly applied in the analytical detection of PCP in real water environments. (C) 2017 Elsevier B.V. All rights reserved.