Time resolved microwave conductivity (TRMC) measurements show that the presence of Au on anatase Hombikat UV100 significantly reduces the lifetime of mobile electrons formed by photo-excitation of this photocatalyst at 300 nm, providing evidence for the widely acclaimed electron localization effect of Au in promoting TiO(2) photocatalysts. Electron localization efficiency of Au was even higher for Au-promoted Hombikat calcined at 400 degrees C, explained by enlargement of the anatase particle size and the associated, relatively larger fraction of anatase particles in direct contact with Au.