Alumina supports with a very narrow pore size distribution were obtained with indium-doped alumina prepared by the sol-gel method. The formation of aluminum in pentahedral coordination was identified by Al-27 NMR-MAS-spectroscopy. A good correlation was obtained with the (AlNMR)-N-V-MAS intensity signal and the activity in isopropanol dehydration. The insertion of In3+ substituting some Al3+ in the alumina network was suggested.