Through current efficiency measurements, obtained from the photoelectrochemical oxidation at TiO2 (rutile)/Ti anodes, further mechanistic information has been obtained regarding the TiO2 photosensitized oxidation of benzylic alcohols, ethers and 1,2-diols in CH3CN. In deaerated medium, two electrons are captured by the semiconductor from all the considered substrates (one from the substrate, the second from the intermediate benzylic radical). In contrast, in aerated CH3CN, the number of TiO2-captured electrons can be reduced to one because, depending on its oxidizability, the benzylic radical can be competitively captured by oxygen. Copyright (c) 2008 John Wiley & Sons, Ltd.