Au nanoparticles (AuNPs) were electrodeposited at the highly ordered anatase TiO2 nanotube array (TiO(2)NA) electrode under sonicating, and the AuNP-TiO(2)NA sensor was characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD). The photoelectrochemical experiments indicate the AuNP-TiO(2)NA sensor has lower photoelectro-resistance, higher photoelectrocatalytical activity and stability than that of pure TiO(2)NA sensor under the same conditions. The as-prepared sensor can be used for the determination of chemical oxygen demand (COD) in real samples, and the obtained results are comparable well with those of by standard K2Cr2O7 method. The method proposed is simple, fast, cost effective, and environmentally friendly. (C) 2018 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.