A novel composite film based on Dawson-type phosphovanadotungstate K8P2W16V2O62 center dot 18H(2)O (P2W16V2) decorated by Au-Pd alloy nanoparticles (Au-Pd) was fabricated on quartz, silicon and ITO using the layer-by-layer self-assembly method. The composite film was characterized by UV-vis spectroscopy, X-ray photoelectron spectra, atomic force microscopy, Scanning electronic microscope, cyclic voltammetry and differential pulse voltammetry. The composite film can be employed for sensitive and simultaneous determination of dopamine and ascorbic acid at biological pH (pH 7.0). Linear analytical curves were obtained in the ranges from 2.1 x 10(-6) to 2.06 x 10(-3) M and 1.2 x 10(-6) to 1.61 x 10(-3) M for dopamine and ascorbic acid by DPV methods, respectively. The low detection limit for dopamine and ascorbic acid were 8.3 x 10(-7) and 4.3 x 10(-7) M, as well as no interference was observed from the common interfering species such as glucose, uric acid, L-cysteine, CH3OH, CH3CH2OH and H2O2. The composite film was used for dopamine and ascorbic acid determinations in real samples with satisfactory results. With high sensitivity and selectivity, the proposed electrochemical sensor would provide a simple method for simultaneous determination of dopamine and ascorbic acid in practical applications. (C) 2013 Elsevier Ltd. All rights reserved.