In this study, acetone formation was investigated as a side reaction in furfural hydrotreatment applying isopropanol as a solvent. Acetone formation was observed to depend strongly on the metal and metal loading of catalysts as copper, nickel, and iron catalysts supported on activated carbon were studied. Furfural has an important role in acetone formation: the initial formation rate for acetone was high as long as furfural reacted further. After furfural was consumed the acetone formation decelerated except with the catalysts including iron. Two formation mechanisms were derived: first mechanism includes direct and transfer hydrogenation of furfural and isopropanol dehydrogenation, as mechanism two consists only of isopropanol dehydrogenation. Another novel discovery of the study was the confirmation of the formation mechanism for 2-methylfuran through transfer hydrogenation of furfuryl alcohol in the experiments. In conclusion, the acetone formation as a side product was observed significant and could not be totally prevented.