Dedicatedi nm emory of Prof.Y iannis Elemes,r emembering the stimulating scientific discussionsa nd friendship.Supporting information for this article is availableonthe WWW under http://dx.doi.org/10.1002/adsc.201500957.Abstract: In this article,t he catalytic activity of titania-supported gold nanoparticles (Au/TiO 2 )w as studied for the selective oxidation of aminesi nto nitroso compounds using hydrogen peroxide (H 2 O 2 ). Gold nanoparticles deposited on DegussaP 25 polymorphso ft itania (TiO 2 )h ave been found to promote the selective formation of av ariety of nitroso arenes in high yields and selectivities,e ven in al arge-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions.K inetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality.AHammett-type kinetic analysiso farange of para-X-substituteda ryl aminesi mplicates an electront ransfer (ET) mechanism (1 = À1.15) for oxidation reactions with concomitant formation of the corresponding Naryl hydroxylamine as possible intermediate.W ea lso show that the oxidation protocolo fa ryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene andthe in situ formed nitrosoarenes.