In recent years, there have been significant efforts to find novel photocatalytic materials with improved properties. Thus, there is an active ongoing search for new materials that can operate at a broad range of wavelengths for photocatalytic reactions. Among photocatalytically active semiconductors, considerable attention has been given to tungsten oxide with a band gap of E-g approximate to 2.6 eV, which provides the opportunity to harvest visible light. In the present work, we report on a one-step synthesis of c-WO3-x/WO(3)xH(2)O nanowhiskers dispersed in a hydrolytically stable mesoporous polycarbosilane-siloxane ([-Si(O)CH2-](n)) matrix. The as-synthesized nanocomposites possess high photocatalytic activity for the degradation of methylene blue (MB) under visible light irradiation. The enhanced photocatalytic activity is due to (i) the reduction in the electron-hole recombination rate because of the reduced dimensions of nanowhiskers, (ii) more efficient consumption of photogenerated electrons and holes as a result of the high surface-to-bulk-ratio of the nanowhiskers, and (iii) better electron-hole pair separation due to the formation of c-WO3-x/WO(3)xH(2)O nanoheterostructures.