Mesoporous nanocrystalline gamma-alumina was prepared by a template-free sol-gel method using aluminum ethoxide as precursor. Significant parameters, such as the water/aluminum ethoxide molar ratio, the pH of the solution, and the time and temperature of aging, were optimized by the Taguchi method to obtain g-alumina with a high surface area and pore volume. The influences of the main parameters on the catalytic performance of the prepared catalysts were investigated via dehydration of methanol to dimethyl ether in a fixed-bed reactor. The catalysts were characterized by X-ray diffraction, N-2 adsorption-desorption, ammonia temperature-programmed desorption, and scanning electron microscopy techniques. The results show that the aging temperature had a significant influence on the catalyst performance.