Boehmites (Al2O3·xH2O) were hydrothermally prepared from aluminum alkoxide. The effect of temperature on preparation was studied in the range of 100-180 ℃. The XRD analysis shows that with temperature increasing, the transformation of pseudo-boehmite into well-crystallized boehmite takes place. The micro-morphologies change also from irregular clew to thin cubic platelets. From the mass loss of the samples prepared at different temperatures, the value of x is estimated to vary between 1.06 and 1.67. γ-Al2O3 obtained by subsequent calcination of boehmite at 600 ℃ is also characterized by XRD and its morphology remains unchanged.