Niobium oxide (Nb2O5) has been prepared from a precursor solution of NbCl5 in ethanol. The effect of pH, water content for hydrolysis and calcination temperature on microstructural, spectroscopic and acidic properties has been studied using N-2 adsorption, X-ray diffraction (XRD), FTIR spectroscopy, temperature programmed desorption (TPD) of ammonia and DRIFTS of adsorbed ammonia. The activity for the aldol condensation of acetone was studied as well.