The photocatalytic activity of titanium dioxide-based photocatalysts obtained either by gold nanoparticles deposition or immobilisation of gold preformed sols on TiO₂, or synthesised by flame spray pyrolysis starting from gold containing Ti-isopropoxide precursor solutions, was tested both in the oxidative degradation of organic substrates of different nature and in the parallel hydrogen peroxide production in the presence of dioxygen. The photocatalytic hydrogen production from water photosplitting or from methanol photoreforming under an inert atmosphere were also employed as test reactions. The different activities of the various Au/TiO₂ samples could be related to their surface, cristallographic and textural properties, as well as to the size and oxidation state of gold nanoparticles. While the presence of gold was usually found to be beneficial in increasing the rate of all photoreductive paths, much minor and often controversial effects could be noticed in the oxidative photocatalytic degradation of organic compounds. This excludes a relevant role of gold nanoparticles in ensuring a better electron-hole separation after photocatalyst excitation. Thus, the higher hydroxyl radical production detected in preliminary electron spin trapping tests does not ensure higher oxidative degradation rates and most probably does not result from water oxidation by valence band holes, but from photoproduced hydrogen peroxide reduction by conduction band electrons.