The phosphated mesoporous TiO2 (PMT) were synthesized by using evaporation-induced self-assembly approach (EISA) with phosphorus content from 1 to 15 mol%. The X-ray diffraction and N-2 adsorption-desorption isothermal results reveal that the incorporating of phosphorus is of benefit to improving the thermal stability and enhancing the surface area of mesoporous TiO2 by constraining the growth of anatase crystallite. XPS confirms the phosphorus in the calcined PMT exists as amorphous titanium phosphate in a pentavalent-oxidation state (P5+) and embedded into the nanocrystalline anatase TiO2. In photodegradation gas phase acetaldehyde, the photocatalytic activity of PMT samples is higher than that of pure mesoporous TiO2 and P25. It is believed that the enhancing photocatalytic activity of phosphated mesoporous TiO2 is mainly caused by two factors relative with the incorporating of phosphorus in framework. (C) 2008 Elsevier B.V. All rights reserved.