Multi-structural tungsten oxide (WO3 center dot 0.33H(2)O) samples were prepared using a hydrothermal method in the presence of different salts Na2SO4 and CaCl2 respectively. The experimental results showed that pH value of the reaction solution greatly affects crystal morphology of the final products. To explore the photocatalysis originated from nanonetwork hierarchical structure, the photodegradation of methylene blue was carried out under simulated sunlight irradiation. The photocatalytic activity of the WO3 center dot 0.33H(2)O nanonetworks was compared with that of the nanoplates, and the former showed a higher photocatalytic activity owing to its novel hierarchical structure. Our investigation demonstrates that nanonetwork hierarchical structure can promote sunlight absorption due to higher specific surface area.