The liquid-phase hydrogenation of crotonaldehyde has been investigated with silver-manganese mixed oxide catalysts. The catalysts were prepared from metal nitrates and an aqueous sodium hydroxide solution by the co-precipitation method and the impregnation method. The reaction was carried out at 130°-180°C under an initial hydrogen pressure of 50 atm with a 300 ml autoclave containing 10 ml crotonaldehyde, 90 ml hexane and 0.5g of catalyst. Adding manganese to silver catalyst at the atomic ratio of Mn/Ag = 1.5 or above, catalytic activity and trans-2-buten-1-ol selectivity remarkably increased were 98.0 mol % and 72.0%, respectively against 36.6 mol% 2-buten-1-ol yield of no manganese catalyst. The effects of manganese oxide in the catalyst are to inhibit the reduction of amorphous silver oxide to a crystal silver at low temperature, and to cause an increase in the concentration of active silver on the catalyst surface, which probably lead to a high activity and a high selectivity of the catalyst. Reactions between the characteristics of catalyst and activity were examined. It was found that the Lewis acid site contributed to the improvement of 2- buten-1-ol yield.