Υ-Alumina was prepared from aluminum hydroxide which was precipitated at different pH by ammonia and calcined at various temperatures. The nitrogen sorption isotherms of γ-alumina were measured at liquid nitrogen temperature and their BET surface areas, pore volumes and pore size distributions from desorption branches of the isotherms were obtained. The acidic properties by ammonia TPD, pyridine-FT-IR and the scanning electron micro-scopy were also studied. All the alumina obtained in this study were γ-alumina. The pore size obtained from adsorption branch increased from 4nm to 6.5nm with the calcination temperature for aluminum hydroxides precipitated at pH 9.65 size. Bimodal pore size distribution obtained having highest peak at 3nm and 5nm for the sample calcined at 500℃. Pore structure of alumina was the ink-bottle type for the alumina precipitated at less than pH9, but the slit type appeared for the alumina precipitated at more than pH 9. Bimodal pore size distribution was also obtained for two alumina precipitated at pH 9.25 and 9.5. The ammonia desorption temperatures in ammonia-TPD for the samples were 110℃, 340℃ and 590℃. The new strong acid site at 720℃ appeared increasing calcination temperature.