Surface Engineering Research SummaryMonoclinic tungsten oxide nanoparticles were successfully grown on a tungsten surface by thermal evaporation. Scanning-electron microscopy showed fairly smooth morphologies for tungsten oxide nanorods. High-resolution transmission-electron microscopy and electron-energy-loss spectroscopy revealed the presence of a high-quality and crystalline monoclinic W 18 O 49 phase. This study offers a feasible route for large-scale production of nanostructured W 18 O 49 .