The catalytic properties of two series of Au/TiO₂ catalysts prepared by deposition-precipitation with NaOH (DP NaOH) (3 wt%) and by deposition-precipitation with urea (DP Urea) (8 wt%) were evaluated for the reaction of crotonaldehyde hydrogenation at atmospheric pressure. There is no difference in activity (mol g_Au⁻¹ s⁻¹) and selectivity between the DP Urea and DP NaOH samples for a given activation treatment. This is due to the fact that the DP Urea and DP NaOH samples exhibit a similar gold particle size distribution, although the gold loading in DP Urea catalysts is much higher than in DP NaOH. The DP Urea samples were reduced under H₂ at different temperatures (120–500 °C) or treated in air at 300 °C with various flow rates, to vary the average particle size within a large range, 1.7 to 8.7 nm. The selectivity to crotyl alcohol (selective hydrogenation of the carbonyl bond), in the 5–50% conversion range, is high, 60–70 %, and is independent of the reduction temperature, and almost constant as a function of the particle size. In contrast, the TOF depends on the gold particle size, drastically increasing when the gold particle size is 2 nm. These characteristic features of Au/TiO₂ catalysts in this reaction are compared with those of Pt/TiO₂. The possible adsorption modes of crotonaldehyde are discussed. Hydrogen dissociation is proposed to be the rate-determining step, and to take place on the low-coordinated atoms of the gold particles.