Micrometer-sized silica spheres were prepared using a new pH-induced rapid colloid aggregation method in water-in-oil (W/O) emulsion separately with F127 and the mixture of Pluronic triblock copolymer (F127 P123, or P105) and PEG20000 as templates. All the mesoporous silica spheres exhibited high surface areas (657-1145 m(2)/g) and large pore volumes (0.46-2.16 ml/g). Through optimizing the synthetic conditions, hard silica spheres with narrow particle size distribution, uniform pore size. and textural pores were obtained. Finally, the mechanism of this synthetic route is discussed. (c) 2006 Elsevier Inc. All rights reserved.