Alumina precursors were prepared by hydrothermal treatment of an alkoxide derived-alcogel. By selection of appropriate hydrothermal conditions aluminas with a variety of pore distributions were obtained, a nd the po re radi us can be easily controlled from 5.0 to 23.5 nm. The hydrothermal conditions were found to strongly affect pore size distribution : (i) elevating the hydrothermal temperature and increasing the time increased the particle size of boehmite, resulting in the above average pore radius of the aluminas; (ii) the alumina obtained from HT-270-10 had an average pore radius of approximately 20 nm and greater than or equal to 1 ml g(-1) pore volume, which were maintained until 1000 degrees C. After heating at 1200 degrees C for 5 h, their values were 17.9 nm and 0.45 ml g(-1), respectively; (iii) the hydrothermal treatment with ethanol gave boehmites with a large particle size and aluminas with a sharp pore distribution and small pore radius. These results were explained by differences in the three-dimensional structures formed by the hydrothermal treatments.