The surface chemical functionalization generally endows gold nanoparticles (Au-NPs) with expanding applications in sensors, medicine and catalysis because of the synergistic effect. In this work, we report a novel strategy for the synthesis of phosphonate functionalized Au-NPs (P-Au-NPs) by using vinylphosphonic acid as the reducing agent and stabilizing agent. The morphology, composition, and structure of P-Au-NPs are fully characterized by various spectroscopy techniques. The resultant P-Au-NPs show a remarkable colloidal stability, which likely arises from strong electrostatic effect of negatively charged phosphonate groups and the extremely hydrophilic property of phosphonate groups. In addition, the as-prepared P-Au-NPs effectively bind Ru-III ions via coordination interaction, which can be used to construct an iodate amperometric sensor with the wide linear range and low detection limit. (C) 2015 Elsevier Ltd. All rights reserved.