Novel nanostructured tungsten trioxide (WO3) films with strong photocatalytic activity, have been prepared by a simple sol-gel route from aqueous peroxopolytungstic acid (PTA) precursor solutions. We demonstrate that films with different morphologies can be synthesized by simply adjusting the pH of this precursor solution using different mineral acids such as HCl and HC1O(4), and that this control of film texture represents a way of optimizing photocurrent yield. The best films produced using these methods generated anodic photocurrents of 3.8 mA/cm(2) for oxidiation of methanol and 2.2 mA/cm(2) for water splitting, under AM1.5 simulated solar illumination.