Abstract Mesoporous γ-aluminas are prepared via a facile one-pot hydrothermal method using aluminum sulfate as a precursor, urea as precipitating agents, sodium tartrate and CTAB (cetyltrimethylammonium bromide) as co-templates respectively. Characterizations of the intermediate aluminum oxyhydroxides by IR, XRD, element analysis and TG show that the amounts of CTAB occluded in the as-prepared mesoporous aluminum oxyhydroxides are determined by molar ratio of sodium tartrate to aluminum (ST/Al). Especially, no sodium tartrate is added, no CTAB is occluded in the mesoporous aluminum oxyhydroxides. The structures of obtained mesoporous aluminas are characterized by XRD, nitrogen adsorption analysis, and scanning electron micrographs (SEM). And the surface areas, mesopore volume and the order of meso-structure are enhanced with an increase in ST/Al molar ratio. Sodium citrate and sodium succinate are also used as additives to study the formation mechanism of organized mesoporous aluminas. The formation mechanisms are proposed that tartrate interacts with aluminum and CTAB simultaneously to form an intermediate as the building blocks of the final meso-structured hybrid.