The hydrogenation of cinnamaldehyde was investigated using a 5% Pd/C catalyst in a 250 cm(3) stirred tank reactor and 500 cm(3) autoclave. The experiments were carried out at 273-343 K and 0.1-1.1 MPa. Non-polar solvents, e.g. toluene, decane, methylcyclohexane, decalin, ether and heptane, and polar solvents such as methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and butan-2-ol were used to study the selectivity with respect to hydrocinnamaldehyde formation, the reaction kinetics and mass transfer. The additives, such as potassium acetate, ferrous chloride, ferrous sulphate and quinoline were incorporated into the catalyst in order to improve the catalyst selectivity, which was observed especially in the case of potassium acetate.