Monoclinic WO3 nanoparticles were synthesized by a simple acid catalyzed co-precipitation reaction. Spherical particles with average size similar to 55 nm were confirmed from electron microscopy followed by functional, structural and optical characterizations. The adsorption of methylene blue was examined by using WO3 nanoparticles and the capacity was higher than most of the reported studies. The effect of pH and material loading on adsorption was determined. The mechanism of adsorption was examined by XPS and a detailed explanation of surface phenomena was proposed. Regeneration study was carried and a high stability of heat treated WO3 towards adsorption of methylene blue was observed. (C) 2017 Elsevier B.V. All rights reserved.