Hollow silica nanospheres with high specific surface area were prepared by a sol-gel route using CaCO₃ nanoparticles as novel templates and sodium silicate as the silica source, followed by calcination, washing in acidic solution and a drying treatment. The samples were characterized by TEM, SEM, BET, EDS, XRD, FTIR and TG. The morphology and the BET of the prepared hollow silica were influenced by the synthesis conditions such as reaction temperature, pH, calcination temperature and SiO₂/CaCO₃ ratio, and the results indicated that hollow silica nanospheres with good morphology and large BET could be obtained under the conditions of SiO₂/CaCO₃＝10%, a reactive temperature of 60—80 ℃, pH≈9 and a calcination temperature of 700 ℃.

Key words: sol-gel, core/shell structure, hollow silica, BET surface area