Monoclinic WO3 (m-WO3) nanoplates and nanorods were successfully synthesized by a simple hydrothermal process using sodium tungstate dihydrate (Na2WO4 2H(2)O) ammonium nitrate (NH4NO3) and polyethylene glycol (PEG) as initial precursors Phase morphologies and electrochemical properties of the products were characterized by X-ray diffraction (XRD) scanning and transmission electron microscopy (SEM TEM) high-resolution transmission electron microscopy (HRTEM) cyclic voltammetry (CV) and linear sweep voltammetry (LSV) The effect of NH4NO3 concentration on the formation of the pure phase of m-WO3 nanomaterial was studied The product synthesized under NH4NO3-free condition was pure orthorhombic WO3 0 33H(2)O (o-WO3 0 33H(2)O) phase By adding and increasing the amount of NH4NO3 to the solution m-WO3 phase started to form and became pure m-WO3 phase when 1 50 g NH4NO3 was used The morphology of m-WO3 was nanoplates and became nanorods by PEG adding The nanostructured m-WO3 showed much higher electrocatalytic activity for hydrogen evolution from water than that of the commercial bulk m-WO3 including the m-WO3 nanorods with slightly better than the m-WO3 nanoplates (C) 2010 Elsevier B V All rights reserved