The aqueous-phase hydrogenation of propanoic acid was performed over the Ru/ZrO2 and Ru/Al2O3 catalysts with different Ru loading. Combined with multiple characterization techniques, such as H-2-TPR, XRD, CO-FTIR, and DRIFTS of propanoic acid, the effect of Ru loading on the decarbonylation/hydrogenation of propanoic acid was investigated. Although hydrogenation/decarbonylation of carboxylic acids were strongly affected by the nature of supports, the increase of metal loading can cause the larger Ru particles and more bare Ru metal sites, which can facilitate the C-C bond cleavage reaction derived from the decarbonylation of propanoyl species over Ru metal sites. [GRAPHICS]