A graphenated polyaniline/tungsten oxide (PANI/WO3/GR) nanocomposite sensor was prepared by electropolymerisation of a mixture of aniline monomer and tungsten oxide on a graphene-modified glassy carbon electrode (GCE). The PANI/WO3/GR/GCE nanocomposite electrode was tested as a sensor for the determination of phenanthrene. The direct electro-oxidation behaviour of phenanthrene on the PANI/WO3/GR modified GCE was carefully investigated by cyclic voltammetry. The results indicated that the PANI/WO3/GR/GCE sensor was more sensitive to phenanthrene (with a dynamic linear range of 1.0-6.0 pM and a detection limit of 0.123 pM.) than GCE, PANI/GCE or PANI/WO3/GCE. The sensor exhibited excellent reproducibility and long-term stability. The sensor exhibits lower detection sensitivity than the WHO permissible level of 1.12 nM phenanthrene in wastewater. (C) 2014 Elsevier Ltd. All rights reserved.