In this work, hierarchical WO3 hollow shells: dendrites, spheres and dumbbells have been successfully synthesized by simply calcining the acid-treated PbWO4 and SrWO4 as precursors at 500 degrees C for 2h. These hollow structures were characterized using X-ray diffraction, scanning and transmission electron microscopies, Brunauer-Emmet-Teller surface area and diffuse reflectance spectroscopy, respectively. Possible formation mechanisms for hollow WO3 shells consisted of tiny nanoplatelets were investigated in detail. Comparing with commercial WO3 particles, all the obtained hollow shells with larger BET surface areas showed enhanced photocatalytic activities for the degradation of organic contaminants under visible light irradiation.