We report the catalytic gas phase hydrogenation of p-nitrobenzonitrile (p-NBN) to paminobenzonitrile (p-ABN) over a series of oxide (CeO 2 , Fe 2 O 3 , Fe 3 O 4 , TiO 2 , ZrO 2 and Al 2 O 3) supported (1 mol%) Au catalysts (mean size 3-8 nm from electron microscopy). Hydrogenation rate was structure sensitive with lower turnover frequencies (TOF) over larger Au nanoparticles in the 4-8 nm interval and a decrease in TOF for Au ≤ 3 nm. This size dependence also applies to H 2 chemisorption under reaction conditions. Rate normalised with respect to H 2 uptake showed a dependence on support redox potential where the formation of oxygen vacancies (from O 2 titration) served to stabilise the −NO 2 group, lowering reactivity. Reaction over Au/TiO 2 with modified electronic character (from XPS) deviated from this trend and delivered the highest specific hydrogenation rate, which is attributed to-NO 2 activation at the Au-TiO 2 interface; this effect extends to TiO 2 supported Ag and Pd.