Abstract: A ruthenium-on-alumina catalyst including at least a ruthenium component carried by a porous &agr;-alumina material. The catalyst has a specific surface area (S1) of 7-50 m2/g, and a ratio S1/S2 of the specific surface area of the ruthenium-on-alumina catalyst (S1) to the surface area of the porous &agr;-alumina material (S2) of 3-50. The catalyst has a micropore structure having a pore diameter distribution profile in which at least one peak falls within the range of 5-1,000 angstroms. The catalyst of the invention has excellent crushing strength, and high activity per unit ruthenium weight. Moreover, the catalyst has remarkable heat resistance, maintaining its high activity even at high temperatures of reaction and firing.