Abstract Porous silica nanoparticles with well-defined mesopores and voids are described. The silica nanoparticles are produced in a rapid aerosol process. The evaporation of solvent during aerosol generation induces multiphased assembly confined to an aerosol droplet containing polystyrene spheres/silica, polystyrene spheres/surfactant/silica or microemulsions/silica. After removal of surfactants, polymer spheres, and microemulsion, the resulting materials exhibit controlled meso- and macro-porosity. TEM and nitrogen sorption isotherms have been used to characterize the porous silica particles. The silica particles templated by polystyrene spheres possess 100 nm voids. The surfactants, as secondary templates, are used to form a mesophase to interconnect the macropores. For the microemulsion-templated silica nanoparticles, the porosity and cell size are controlled by the amount of oil and the size of the swelling molecule.