The electron transport in nanostructured TiO2 has been investigated in an electrochem. system using laser flash induced photocurrent transient measurements with addnl. continuous monochromatic bias light. Significant effects are found on the photocurrent transient depending on the wavelength of the bias light (360-480 nm). The electron transport time is shorter and the total collected charge is higher when the bias light is in the UV region, while increased transport times and a decreased charge is found with visible light bias. These effects can be explained by trap filling by the UV bias light in the first case and by emptying of traps by visible bias light in the latter.