Kinetics of the hydrogenation of citral and its intermediates over Ir/TiO2/SiO2 catalysts has been studied. The effect of various parameters such as the initial concentration, H-2 pressure partial, temperature and weight of catalyst were examined. A high selectivity towards unsaturated alcohols using this catalyst was demonstrated. The initial rates increased linearly with the catalyst weight. The reaction rate obeys a kinetics represented by the Langmuir-Hinshelwood model. A single site model suggesting the surface reaction as the rate determining step provided the best fit of the experimental data for the hydrogenation of citral and alcohols (geraniol, nerol and citronellol), while a dual site represent the best kinetics for the hydrogenation of citronellal. (C) 2008 Elsevier B.V. All rights reserved.