This study reports the synthesis of mesoporous nano-fibrillar alumina prepared by hydrolysis-precipitation route from aqueous solution of aluminum sulfate analytical reagent (AR) compared to aluminum sulfate technical grade (TG) of low purity under similar conditions using ammonia as the precipitating agent. The phisicochemical properties of these samples was studied with the assistance of characterization techniques such as Thermogravimetric and differential thermal analysis (TG/DTGA–DTA), X-ray diffraction (XRD), N2 adsorption-desorption isotherms, Fourier transform infrared (FTIR) spectroscopy, particles size and Transmission electron microscopy with energy-dispersive X-ray analysis (TEM/EDAX). The TG-DTA and XRD results show greater stability and a slightly greater crystallinity in Al2O3-TG sample than Al2O3-AR. N2 adsorption-desorption results show for both materials greatly surface area of 311 m2/g for Al2O3-TG and 272 m2/g for Al2O3-AR exhibiting characteristics of mesoporous materials. The FTIR results show a lower percentage of surface OH groups for Al2O3-TG showing a lower acidity due to the lower concentration of Al-OH species (AlIV). TEM measurements confirmed fibers size ranged from 20 to 100 nm for Al2O3-TG and 20-80 nm for Al2O3-AR. EDAX shows the presence of 0.20 % atomic of Mg as an impurity in Al2O3-TG, is attributed that this amount is sufficient to generate structural defects and decrease slightly acidity, likewise, extended the fibrillar chain of the alumina.