Ru-modified MCM-41 mesoporous molecular sieve and Y zeolite catalysts were synthesised and characterised using XRD, electrochemical voltammetry, ESCA (XPS), nitrogen adsorption and H-2-TPD. Selective liquid-phase hydrogenation of cinnamaldehyde to cinnamyl alcohol was investigated over these catalysts and compared to hydrogenation on a commercial Ru/C catalyst. The effect of support (MCM-41, Y and C), solvent (cyclohexane, hexane and 2-propanol) and catalyst pre-treatment (calcination) on the conversion of cinnamaldehyde and selectivity to cinnamyl alcohol was studied. The zeolite structure, pore size, acidity, catalyst pre-treatment as well as the solvent influenced the activity and selectivity. Non-calcined Ru/Y exhibited the highest selectivity to cinnamyl alcohol. The activity of Ru/Y was highest with 2-propanol as a solvent. (C) 2003 Elsevier B.V. All rights reserved.