γ-Al 2 O 3 , dried alumina gel, as well as their phosphated forms using (NH 4 ) 2 HPO 4 were prepared by wet impregnation and calcined at 870 K. Resulted samples were subjected to investigate the consequent bulk [X-ray powder diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and infrared spectroscopy (IR)] and surface (texture, N 2 -adsorption and surface acid properties, pyridine adsorption). Results indicated no detectable bulk phase changes due to phosphation. However, the phosphated gel sample reveals the highest S B E T . Surface stabilization of phosphate species by γ-Al 2 O 3 or gel is indicated, leading to modifications on surface hydroxyl and hence surface acidity. The phosphated gel sample exhibits the strongest acidity (both Bronsted and Lewis).