Three-dimensional coral-like Pt nanochains (Pt-3DCNCs) are synthesized in high yields by a simple hydrothermal reduction using HCHO as a reductant agent in the presence of NaI but without any other templates or surfactants. The size, composition, and structure of Pt-3DCNCs are inspected by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The controlled experiment show the introduction of NaI is the key influential factor for the formation of the specific structure of Pt-3DCNCs. The as-prepared Pt-3DCNCs show superior electrocatalytic activity and long-term stability towards oxygen reduction reaction, which can be ascribed to their unique structure and the low hydroxyl surface coverage. (C) 2015 Elsevier Ltd. All rights reserved.