Liquid phase pentanoic acid hydrogenation in decane as a solvent (180ºC, hydrogen pressure 25 bar) was studied over monometallic Ir and bimetallic Ir-Re catalysts supported on alumina, ceria and zirconia. Before catalytic test all catalysts were preliminary treated in Н₂ at 415ºC during 5 h. An XPS study revealed metallic state for Ir in studied catalysts while Re was partially oxidized. Conversion of pentanoic acid changed in the row Ir/CeO₂ < Ir/ZrO₂ < IrRe/ZrO₂ < IrRe/Al₂O₃. Selectivity to pentanol was elevated over bimetallic catalysts in the sequence Ir/Al₂O₃ < Ir/CeO₂ ~ Ir/ZrO₂ < IrRe/ZrO₂ < IrRe/Al₂O₃. It was shown that doping of Ir with Re gives a rise of pentanoic acid conversion and selectivity to pentanol in the absence of by-side decarboxylation reaction. A series of the most active catalyst IrRe/Al₂O₃ was prepared varying Ir particle size from 0.8 to 1.7 nm as verified by TEM. Both pentanoic acid conversion and selectivity to pentanol over IrRe/Al₂O₃ catalyst increased with an increase of mean Ir particle size.