Various single-phase aluminum oxides were prepared through the thermal decomposition of bayerite, boehmite, and gibbsite. Ni/gamma-Al2O3 and Ni/delta-Al2O3 catalysts exhibited higher monoisopropylamine (MIPA) selectivity than the eta-, theta-, and kappa-Al2O3 supported Ni catalysts for the reductive amination of 2-propanol (IPA) in the presence of hydrogen and ammonia. FT-IR spectra after pyridine adsorption showed that a high number of Lewis acid sites could be correlated with enhancement in MIPA selectivity. Ni/eta-Al2O3 and Ni/gamma-Al2O3 catalysts exhibited the highest catalytic activity arising from differences in the metallic surface area. Both catalyst activity and selectivity with regards to reductive amination were strongly affected by the nature of the support.