Spherical porous silica microparticles were synthesized by a sol-gel process in the presence of porous CaCO3 particles,followed by removal of the carbonate templates.The resulting silica particles had very high porosity and wide pore size distribution,whose surface area and pore volume reached up to 367.3 m2/g and 0.72 mL/g,respectively.With a larger amount of the tetraethyl orthosilicate used,hollow silica mierospheres were further obtained.Characterization was made to confirm the chemical and physical structures and purity of the silica microspheres.Spontaneous deposition of tetramethyl rhodamine isothiocyanate labeled dextran into the mierospheres was also observed due to the charge attraction.